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llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp

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//===------- ItaniumCXXABI.cpp - Emit LLVM Code from ASTs for a Module ----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ code generation targeting the Itanium C++ ABI. The class
// in this file generates structures that follow the Itanium C++ ABI, which is
// documented at:
// http://www.codesourcery.com/public/cxx-abi/abi.html
// http://www.codesourcery.com/public/cxx-abi/abi-eh.html
//
// It also supports the closely-related ARM ABI, documented at:
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
//
//===----------------------------------------------------------------------===//
#include "CGCXXABI.h"
#include "CGRecordLayout.h"
#include "CGVTables.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/Type.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Value.h"
using namespace clang;
using namespace CodeGen;
namespace {
class ItaniumCXXABI : public CodeGen::CGCXXABI {
/// VTables - All the vtables which have been defined.
llvm::DenseMap<const CXXRecordDecl *, llvm::GlobalVariable *> VTables;
protected:
bool UseARMMethodPtrABI;
bool UseARMGuardVarABI;
ItaniumMangleContext &getMangleContext() {
return cast<ItaniumMangleContext>(CodeGen::CGCXXABI::getMangleContext());
}
public:
ItaniumCXXABI(CodeGen::CodeGenModule &CGM,
bool UseARMMethodPtrABI = false,
bool UseARMGuardVarABI = false) :
CGCXXABI(CGM), UseARMMethodPtrABI(UseARMMethodPtrABI),
UseARMGuardVarABI(UseARMGuardVarABI) { }
bool classifyReturnType(CGFunctionInfo &FI) const override;
RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {
// Structures with either a non-trivial destructor or a non-trivial
// copy constructor are always indirect.
// FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
// special members.
if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor())
return RAA_Indirect;
return RAA_Default;
}
bool isZeroInitializable(const MemberPointerType *MPT) override;
llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override;
llvm::Value *
EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
const Expr *E,
llvm::Value *&This,
llvm::Value *MemFnPtr,
const MemberPointerType *MPT) override;
llvm::Value *
EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E,
llvm::Value *Base,
llvm::Value *MemPtr,
const MemberPointerType *MPT) override;
llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *Src) override;
llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *Src) override;
llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override;
llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD) override;
llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) override;
llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override;
llvm::Constant *BuildMemberPointer(const CXXMethodDecl *MD,
CharUnits ThisAdjustment);
llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L, llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality) override;
llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *Addr,
const MemberPointerType *MPT) override;
void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE,
llvm::Value *Ptr, QualType ElementType,
const CXXDestructorDecl *Dtor) override;
void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
void EmitFundamentalRTTIDescriptor(QualType Type);
void EmitFundamentalRTTIDescriptors();
llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
void EmitBadTypeidCall(CodeGenFunction &CGF) override;
llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy,
llvm::Value *ThisPtr,
llvm::Type *StdTypeInfoPtrTy) override;
bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
QualType SrcRecordTy) override;
llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value,
QualType SrcRecordTy, QualType DestTy,
QualType DestRecordTy,
llvm::BasicBlock *CastEnd) override;
llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, llvm::Value *Value,
QualType SrcRecordTy,
QualType DestTy) override;
bool EmitBadCastCall(CodeGenFunction &CGF) override;
llvm::Value *
GetVirtualBaseClassOffset(CodeGenFunction &CGF, llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) override;
void EmitCXXConstructors(const CXXConstructorDecl *D) override;
void buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
SmallVectorImpl<CanQualType> &ArgTys) override;
bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
CXXDtorType DT) const override {
// Itanium does not emit any destructor variant as an inline thunk.
// Delegating may occur as an optimization, but all variants are either
// emitted with external linkage or as linkonce if they are inline and used.
return false;
}
void EmitCXXDestructors(const CXXDestructorDecl *D) override;
void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
FunctionArgList &Params) override;
void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override;
unsigned addImplicitConstructorArgs(CodeGenFunction &CGF,
const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
bool Delegating,
CallArgList &Args) override;
void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
CXXDtorType Type, bool ForVirtualBase,
bool Delegating, llvm::Value *This) override;
void emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) override;
llvm::Value *getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass,
BaseSubobject Base, const CXXRecordDecl *NearestVBase,
bool &NeedsVirtualOffset) override;
llvm::Constant *
getVTableAddressPointForConstExpr(BaseSubobject Base,
const CXXRecordDecl *VTableClass) override;
llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) override;
llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD,
llvm::Value *This,
llvm::Type *Ty) override;
llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor,
CXXDtorType DtorType,
llvm::Value *This,
const CXXMemberCallExpr *CE) override;
void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override;
void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, GlobalDecl GD,
bool ReturnAdjustment) override {
// Allow inlining of thunks by emitting them with available_externally
// linkage together with vtables when needed.
if (ForVTable)
Thunk->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
}
llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This,
const ThisAdjustment &TA) override;
llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
const ReturnAdjustment &RA) override;
size_t getSrcArgforCopyCtor(const CXXConstructorDecl *,
FunctionArgList &Args) const override {
assert(!Args.empty() && "expected the arglist to not be empty!");
return Args.size() - 1;
}
StringRef GetPureVirtualCallName() override { return "__cxa_pure_virtual"; }
StringRef GetDeletedVirtualCallName() override
{ return "__cxa_deleted_virtual"; }
CharUnits getArrayCookieSizeImpl(QualType elementType) override;
llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) override;
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize) override;
void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
llvm::GlobalVariable *DeclPtr,
bool PerformInit) override;
void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
llvm::Constant *dtor, llvm::Constant *addr) override;
llvm::Function *getOrCreateThreadLocalWrapper(const VarDecl *VD,
llvm::Value *Val);
void EmitThreadLocalInitFuncs(
CodeGenModule &CGM,
ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *>>
CXXThreadLocals,
ArrayRef<llvm::Function *> CXXThreadLocalInits,
ArrayRef<llvm::GlobalVariable *> CXXThreadLocalInitVars) override;
bool usesThreadWrapperFunction() const override { return true; }
LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD,
QualType LValType) override;
bool NeedsVTTParameter(GlobalDecl GD) override;
/**************************** RTTI Uniqueness ******************************/
protected:
/// Returns true if the ABI requires RTTI type_info objects to be unique
/// across a program.
virtual bool shouldRTTIBeUnique() const { return true; }
public:
/// What sort of unique-RTTI behavior should we use?
enum RTTIUniquenessKind {
/// We are guaranteeing, or need to guarantee, that the RTTI string
/// is unique.
RUK_Unique,
/// We are not guaranteeing uniqueness for the RTTI string, so we
/// can demote to hidden visibility but must use string comparisons.
RUK_NonUniqueHidden,
/// We are not guaranteeing uniqueness for the RTTI string, so we
/// have to use string comparisons, but we also have to emit it with
/// non-hidden visibility.
RUK_NonUniqueVisible
};
/// Return the required visibility status for the given type and linkage in
/// the current ABI.
RTTIUniquenessKind
classifyRTTIUniqueness(QualType CanTy,
llvm::GlobalValue::LinkageTypes Linkage) const;
friend class ItaniumRTTIBuilder;
void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) override;
};
class ARMCXXABI : public ItaniumCXXABI {
public:
ARMCXXABI(CodeGen::CodeGenModule &CGM) :
ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
/* UseARMGuardVarABI = */ true) {}
bool HasThisReturn(GlobalDecl GD) const override {
return (isa<CXXConstructorDecl>(GD.getDecl()) || (
isa<CXXDestructorDecl>(GD.getDecl()) &&
GD.getDtorType() != Dtor_Deleting));
}
void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV,
QualType ResTy) override;
CharUnits getArrayCookieSizeImpl(QualType elementType) override;
llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) override;
llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, llvm::Value *allocPtr,
CharUnits cookieSize) override;
};
class iOS64CXXABI : public ARMCXXABI {
public:
iOS64CXXABI(CodeGen::CodeGenModule &CGM) : ARMCXXABI(CGM) {}
// ARM64 libraries are prepared for non-unique RTTI.
bool shouldRTTIBeUnique() const override { return false; }
};
}
CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {
switch (CGM.getTarget().getCXXABI().getKind()) {
// For IR-generation purposes, there's no significant difference
// between the ARM and iOS ABIs.
case TargetCXXABI::GenericARM:
case TargetCXXABI::iOS:
return new ARMCXXABI(CGM);
case TargetCXXABI::iOS64:
return new iOS64CXXABI(CGM);
// Note that AArch64 uses the generic ItaniumCXXABI class since it doesn't
// include the other 32-bit ARM oddities: constructor/destructor return values
// and array cookies.
case TargetCXXABI::GenericAArch64:
return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
/* UseARMGuardVarABI = */ true);
case TargetCXXABI::GenericItanium:
if (CGM.getContext().getTargetInfo().getTriple().getArch()
== llvm::Triple::le32) {
// For PNaCl, use ARM-style method pointers so that PNaCl code
// does not assume anything about the alignment of function
// pointers.
return new ItaniumCXXABI(CGM, /* UseARMMethodPtrABI = */ true,
/* UseARMGuardVarABI = */ false);
}
return new ItaniumCXXABI(CGM);
case TargetCXXABI::Microsoft:
llvm_unreachable("Microsoft ABI is not Itanium-based");
}
llvm_unreachable("bad ABI kind");
}
llvm::Type *
ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
if (MPT->isMemberDataPointer())
return CGM.PtrDiffTy;
return llvm::StructType::get(CGM.PtrDiffTy, CGM.PtrDiffTy, nullptr);
}
/// In the Itanium and ARM ABIs, method pointers have the form:
/// struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr;
///
/// In the Itanium ABI:
/// - method pointers are virtual if (memptr.ptr & 1) is nonzero
/// - the this-adjustment is (memptr.adj)
/// - the virtual offset is (memptr.ptr - 1)
///
/// In the ARM ABI:
/// - method pointers are virtual if (memptr.adj & 1) is nonzero
/// - the this-adjustment is (memptr.adj >> 1)
/// - the virtual offset is (memptr.ptr)
/// ARM uses 'adj' for the virtual flag because Thumb functions
/// may be only single-byte aligned.
///
/// If the member is virtual, the adjusted 'this' pointer points
/// to a vtable pointer from which the virtual offset is applied.
///
/// If the member is non-virtual, memptr.ptr is the address of
/// the function to call.
llvm::Value *ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(
CodeGenFunction &CGF, const Expr *E, llvm::Value *&This,
llvm::Value *MemFnPtr, const MemberPointerType *MPT) {
CGBuilderTy &Builder = CGF.Builder;
const FunctionProtoType *FPT =
MPT->getPointeeType()->getAs<FunctionProtoType>();
const CXXRecordDecl *RD =
cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
llvm::FunctionType *FTy =
CGM.getTypes().GetFunctionType(
CGM.getTypes().arrangeCXXMethodType(RD, FPT));
llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(CGM.PtrDiffTy, 1);
llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual");
llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual");
llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end");
// Extract memptr.adj, which is in the second field.
llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj");
// Compute the true adjustment.
llvm::Value *Adj = RawAdj;
if (UseARMMethodPtrABI)
Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted");
// Apply the adjustment and cast back to the original struct type
// for consistency.
llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy());
Ptr = Builder.CreateInBoundsGEP(Ptr, Adj);
This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted");
// Load the function pointer.
llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr");
// If the LSB in the function pointer is 1, the function pointer points to
// a virtual function.
llvm::Value *IsVirtual;
if (UseARMMethodPtrABI)
IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1);
else
IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1);
IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual");
Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual);
// In the virtual path, the adjustment left 'This' pointing to the
// vtable of the correct base subobject. The "function pointer" is an
// offset within the vtable (+1 for the virtual flag on non-ARM).
CGF.EmitBlock(FnVirtual);
// Cast the adjusted this to a pointer to vtable pointer and load.
llvm::Type *VTableTy = Builder.getInt8PtrTy();
llvm::Value *VTable = CGF.GetVTablePtr(This, VTableTy);
// Apply the offset.
llvm::Value *VTableOffset = FnAsInt;
if (!UseARMMethodPtrABI)
VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1);
VTable = Builder.CreateGEP(VTable, VTableOffset);
// Load the virtual function to call.
VTable = Builder.CreateBitCast(VTable, FTy->getPointerTo()->getPointerTo());
llvm::Value *VirtualFn = Builder.CreateLoad(VTable, "memptr.virtualfn");
CGF.EmitBranch(FnEnd);
// In the non-virtual path, the function pointer is actually a
// function pointer.
CGF.EmitBlock(FnNonVirtual);
llvm::Value *NonVirtualFn =
Builder.CreateIntToPtr(FnAsInt, FTy->getPointerTo(), "memptr.nonvirtualfn");
// We're done.
CGF.EmitBlock(FnEnd);
llvm::PHINode *Callee = Builder.CreatePHI(FTy->getPointerTo(), 2);
Callee->addIncoming(VirtualFn, FnVirtual);
Callee->addIncoming(NonVirtualFn, FnNonVirtual);
return Callee;
}
/// Compute an l-value by applying the given pointer-to-member to a
/// base object.
llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(
CodeGenFunction &CGF, const Expr *E, llvm::Value *Base, llvm::Value *MemPtr,
const MemberPointerType *MPT) {
assert(MemPtr->getType() == CGM.PtrDiffTy);
CGBuilderTy &Builder = CGF.Builder;
unsigned AS = Base->getType()->getPointerAddressSpace();
// Cast to char*.
Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS));
// Apply the offset, which we assume is non-null.
llvm::Value *Addr = Builder.CreateInBoundsGEP(Base, MemPtr, "memptr.offset");
// Cast the address to the appropriate pointer type, adopting the
// address space of the base pointer.
llvm::Type *PType
= CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
return Builder.CreateBitCast(Addr, PType);
}
/// Perform a bitcast, derived-to-base, or base-to-derived member pointer
/// conversion.
///
/// Bitcast conversions are always a no-op under Itanium.
///
/// Obligatory offset/adjustment diagram:
/// <-- offset --> <-- adjustment -->
/// |--------------------------|----------------------|--------------------|
/// ^Derived address point ^Base address point ^Member address point
///
/// So when converting a base member pointer to a derived member pointer,
/// we add the offset to the adjustment because the address point has
/// decreased; and conversely, when converting a derived MP to a base MP
/// we subtract the offset from the adjustment because the address point
/// has increased.
///
/// The standard forbids (at compile time) conversion to and from
/// virtual bases, which is why we don't have to consider them here.
///
/// The standard forbids (at run time) casting a derived MP to a base
/// MP when the derived MP does not point to a member of the base.
/// This is why -1 is a reasonable choice for null data member
/// pointers.
llvm::Value *
ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
const CastExpr *E,
llvm::Value *src) {
assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
E->getCastKind() == CK_BaseToDerivedMemberPointer ||
E->getCastKind() == CK_ReinterpretMemberPointer);
// Under Itanium, reinterprets don't require any additional processing.
if (E->getCastKind() == CK_ReinterpretMemberPointer) return src;
// Use constant emission if we can.
if (isa<llvm::Constant>(src))
return EmitMemberPointerConversion(E, cast<llvm::Constant>(src));
llvm::Constant *adj = getMemberPointerAdjustment(E);
if (!adj) return src;
CGBuilderTy &Builder = CGF.Builder;
bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);
const MemberPointerType *destTy =
E->getType()->castAs<MemberPointerType>();
// For member data pointers, this is just a matter of adding the
// offset if the source is non-null.
if (destTy->isMemberDataPointer()) {
llvm::Value *dst;
if (isDerivedToBase)
dst = Builder.CreateNSWSub(src, adj, "adj");
else
dst = Builder.CreateNSWAdd(src, adj, "adj");
// Null check.
llvm::Value *null = llvm::Constant::getAllOnesValue(src->getType());
llvm::Value *isNull = Builder.CreateICmpEQ(src, null, "memptr.isnull");
return Builder.CreateSelect(isNull, src, dst);
}
// The this-adjustment is left-shifted by 1 on ARM.
if (UseARMMethodPtrABI) {
uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue();
offset <<= 1;
adj = llvm::ConstantInt::get(adj->getType(), offset);
}
llvm::Value *srcAdj = Builder.CreateExtractValue(src, 1, "src.adj");
llvm::Value *dstAdj;
if (isDerivedToBase)
dstAdj = Builder.CreateNSWSub(srcAdj, adj, "adj");
else
dstAdj = Builder.CreateNSWAdd(srcAdj, adj, "adj");
return Builder.CreateInsertValue(src, dstAdj, 1);
}
llvm::Constant *
ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E,
llvm::Constant *src) {
assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
E->getCastKind() == CK_BaseToDerivedMemberPointer ||
E->getCastKind() == CK_ReinterpretMemberPointer);
// Under Itanium, reinterprets don't require any additional processing.
if (E->getCastKind() == CK_ReinterpretMemberPointer) return src;
// If the adjustment is trivial, we don't need to do anything.
llvm::Constant *adj = getMemberPointerAdjustment(E);
if (!adj) return src;
bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer);
const MemberPointerType *destTy =
E->getType()->castAs<MemberPointerType>();
// For member data pointers, this is just a matter of adding the
// offset if the source is non-null.
if (destTy->isMemberDataPointer()) {
// null maps to null.
if (src->isAllOnesValue()) return src;
if (isDerivedToBase)
return llvm::ConstantExpr::getNSWSub(src, adj);
else
return llvm::ConstantExpr::getNSWAdd(src, adj);
}
// The this-adjustment is left-shifted by 1 on ARM.
if (UseARMMethodPtrABI) {
uint64_t offset = cast<llvm::ConstantInt>(adj)->getZExtValue();
offset <<= 1;
adj = llvm::ConstantInt::get(adj->getType(), offset);
}
llvm::Constant *srcAdj = llvm::ConstantExpr::getExtractValue(src, 1);
llvm::Constant *dstAdj;
if (isDerivedToBase)
dstAdj = llvm::ConstantExpr::getNSWSub(srcAdj, adj);
else
dstAdj = llvm::ConstantExpr::getNSWAdd(srcAdj, adj);
return llvm::ConstantExpr::getInsertValue(src, dstAdj, 1);
}
llvm::Constant *
ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
// Itanium C++ ABI 2.3:
// A NULL pointer is represented as -1.
if (MPT->isMemberDataPointer())
return llvm::ConstantInt::get(CGM.PtrDiffTy, -1ULL, /*isSigned=*/true);
llvm::Constant *Zero = llvm::ConstantInt::get(CGM.PtrDiffTy, 0);
llvm::Constant *Values[2] = { Zero, Zero };
return llvm::ConstantStruct::getAnon(Values);
}
llvm::Constant *
ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset) {
// Itanium C++ ABI 2.3:
// A pointer to data member is an offset from the base address of
// the class object containing it, represented as a ptrdiff_t
return llvm::ConstantInt::get(CGM.PtrDiffTy, offset.getQuantity());
}
llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
return BuildMemberPointer(MD, CharUnits::Zero());
}
llvm::Constant *ItaniumCXXABI::BuildMemberPointer(const CXXMethodDecl *MD,
CharUnits ThisAdjustment) {
assert(MD->isInstance() && "Member function must not be static!");
MD = MD->getCanonicalDecl();
CodeGenTypes &Types = CGM.getTypes();
// Get the function pointer (or index if this is a virtual function).
llvm::Constant *MemPtr[2];
if (MD->isVirtual()) {
uint64_t Index = CGM.getItaniumVTableContext().getMethodVTableIndex(MD);
const ASTContext &Context = getContext();
CharUnits PointerWidth =
Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
uint64_t VTableOffset = (Index * PointerWidth.getQuantity());
if (UseARMMethodPtrABI) {
// ARM C++ ABI 3.2.1:
// This ABI specifies that adj contains twice the this
// adjustment, plus 1 if the member function is virtual. The
// least significant bit of adj then makes exactly the same
// discrimination as the least significant bit of ptr does for
// Itanium.
MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset);
MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy,
2 * ThisAdjustment.getQuantity() + 1);
} else {
// Itanium C++ ABI 2.3:
// For a virtual function, [the pointer field] is 1 plus the
// virtual table offset (in bytes) of the function,
// represented as a ptrdiff_t.
MemPtr[0] = llvm::ConstantInt::get(CGM.PtrDiffTy, VTableOffset + 1);
MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy,
ThisAdjustment.getQuantity());
}
} else {
const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
llvm::Type *Ty;
// Check whether the function has a computable LLVM signature.
if (Types.isFuncTypeConvertible(FPT)) {
// The function has a computable LLVM signature; use the correct type.
Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD));
} else {
// Use an arbitrary non-function type to tell GetAddrOfFunction that the
// function type is incomplete.
Ty = CGM.PtrDiffTy;
}
llvm::Constant *addr = CGM.GetAddrOfFunction(MD, Ty);
MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, CGM.PtrDiffTy);
MemPtr[1] = llvm::ConstantInt::get(CGM.PtrDiffTy,
(UseARMMethodPtrABI ? 2 : 1) *
ThisAdjustment.getQuantity());
}
return llvm::ConstantStruct::getAnon(MemPtr);
}
llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const APValue &MP,
QualType MPType) {
const MemberPointerType *MPT = MPType->castAs<MemberPointerType>();
const ValueDecl *MPD = MP.getMemberPointerDecl();
if (!MPD)
return EmitNullMemberPointer(MPT);
CharUnits ThisAdjustment = getMemberPointerPathAdjustment(MP);
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD))
return BuildMemberPointer(MD, ThisAdjustment);
CharUnits FieldOffset =
getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD));
return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset);
}
/// The comparison algorithm is pretty easy: the member pointers are
/// the same if they're either bitwise identical *or* both null.
///
/// ARM is different here only because null-ness is more complicated.
llvm::Value *
ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
llvm::Value *L,
llvm::Value *R,
const MemberPointerType *MPT,
bool Inequality) {
CGBuilderTy &Builder = CGF.Builder;
llvm::ICmpInst::Predicate Eq;
llvm::Instruction::BinaryOps And, Or;
if (Inequality) {
Eq = llvm::ICmpInst::ICMP_NE;
And = llvm::Instruction::Or;
Or = llvm::Instruction::And;
} else {
Eq = llvm::ICmpInst::ICMP_EQ;
And = llvm::Instruction::And;
Or = llvm::Instruction::Or;
}
// Member data pointers are easy because there's a unique null
// value, so it just comes down to bitwise equality.
if (MPT->isMemberDataPointer())
return Builder.CreateICmp(Eq, L, R);
// For member function pointers, the tautologies are more complex.
// The Itanium tautology is:
// (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj))
// The ARM tautology is:
// (L == R) <==> (L.ptr == R.ptr &&
// (L.adj == R.adj ||
// (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0)))
// The inequality tautologies have exactly the same structure, except
// applying De Morgan's laws.
llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr");
llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr");
// This condition tests whether L.ptr == R.ptr. This must always be
// true for equality to hold.
llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr");
// This condition, together with the assumption that L.ptr == R.ptr,
// tests whether the pointers are both null. ARM imposes an extra
// condition.
llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType());
llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null");
// This condition tests whether L.adj == R.adj. If this isn't
// true, the pointers are unequal unless they're both null.
llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj");
llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj");
llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj");
// Null member function pointers on ARM clear the low bit of Adj,
// so the zero condition has to check that neither low bit is set.
if (UseARMMethodPtrABI) {
llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1);
// Compute (l.adj | r.adj) & 1 and test it against zero.
llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj");
llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One);
llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero,
"cmp.or.adj");
EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero);
}
// Tie together all our conditions.
llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq);
Result = Builder.CreateBinOp(And, PtrEq, Result,
Inequality ? "memptr.ne" : "memptr.eq");
return Result;
}
llvm::Value *
ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT) {
CGBuilderTy &Builder = CGF.Builder;
/// For member data pointers, this is just a check against -1.
if (MPT->isMemberDataPointer()) {
assert(MemPtr->getType() == CGM.PtrDiffTy);
llvm::Value *NegativeOne =
llvm::Constant::getAllOnesValue(MemPtr->getType());
return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool");
}
// In Itanium, a member function pointer is not null if 'ptr' is not null.
llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr");
llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0);
llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool");
// On ARM, a member function pointer is also non-null if the low bit of 'adj'
// (the virtual bit) is set.
if (UseARMMethodPtrABI) {
llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1);
llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj");
llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit");
llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero,
"memptr.isvirtual");
Result = Builder.CreateOr(Result, IsVirtual);
}
return Result;
}
bool ItaniumCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
if (!RD)
return false;
// Return indirectly if we have a non-trivial copy ctor or non-trivial dtor.
// FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
// special members.
if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor()) {
FI.getReturnInfo() = ABIArgInfo::getIndirect(0, /*ByVal=*/false);
return true;
}
return false;
}
/// The Itanium ABI requires non-zero initialization only for data
/// member pointers, for which '0' is a valid offset.
bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
return MPT->getPointeeType()->isFunctionType();
}
/// The Itanium ABI always places an offset to the complete object
/// at entry -2 in the vtable.
void ItaniumCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF,
const CXXDeleteExpr *DE,
llvm::Value *Ptr,
QualType ElementType,
const CXXDestructorDecl *Dtor) {
bool UseGlobalDelete = DE->isGlobalDelete();
if (UseGlobalDelete) {
// Derive the complete-object pointer, which is what we need
// to pass to the deallocation function.
// Grab the vtable pointer as an intptr_t*.
llvm::Value *VTable = CGF.GetVTablePtr(Ptr, CGF.IntPtrTy->getPointerTo());
// Track back to entry -2 and pull out the offset there.
llvm::Value *OffsetPtr = CGF.Builder.CreateConstInBoundsGEP1_64(
VTable, -2, "complete-offset.ptr");
llvm::LoadInst *Offset = CGF.Builder.CreateLoad(OffsetPtr);
Offset->setAlignment(CGF.PointerAlignInBytes);
// Apply the offset.
llvm::Value *CompletePtr = CGF.Builder.CreateBitCast(Ptr, CGF.Int8PtrTy);
CompletePtr = CGF.Builder.CreateInBoundsGEP(CompletePtr, Offset);
// If we're supposed to call the global delete, make sure we do so
// even if the destructor throws.
CGF.pushCallObjectDeleteCleanup(DE->getOperatorDelete(), CompletePtr,
ElementType);
}
// FIXME: Provide a source location here even though there's no
// CXXMemberCallExpr for dtor call.
CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting;
EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, /*CE=*/nullptr);
if (UseGlobalDelete)
CGF.PopCleanupBlock();
}
void ItaniumCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) {
// void __cxa_rethrow();
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, /*IsVarArgs=*/false);
llvm::Constant *Fn = CGM.CreateRuntimeFunction(FTy, "__cxa_rethrow");
if (isNoReturn)
CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, None);
else
CGF.EmitRuntimeCallOrInvoke(Fn);
}
static llvm::Constant *getItaniumDynamicCastFn(CodeGenFunction &CGF) {
// void *__dynamic_cast(const void *sub,
// const abi::__class_type_info *src,
// const abi::__class_type_info *dst,
// std::ptrdiff_t src2dst_offset);
llvm::Type *Int8PtrTy = CGF.Int8PtrTy;
llvm::Type *PtrDiffTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
llvm::Type *Args[4] = { Int8PtrTy, Int8PtrTy, Int8PtrTy, PtrDiffTy };
llvm::FunctionType *FTy = llvm::FunctionType::get(Int8PtrTy, Args, false);
// Mark the function as nounwind readonly.
llvm::Attribute::AttrKind FuncAttrs[] = { llvm::Attribute::NoUnwind,
llvm::Attribute::ReadOnly };
llvm::AttributeSet Attrs = llvm::AttributeSet::get(
CGF.getLLVMContext(), llvm::AttributeSet::FunctionIndex, FuncAttrs);
return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast", Attrs);
}
static llvm::Constant *getBadCastFn(CodeGenFunction &CGF) {
// void __cxa_bad_cast();
llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);
return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_cast");
}
/// \brief Compute the src2dst_offset hint as described in the
/// Itanium C++ ABI [2.9.7]
static CharUnits computeOffsetHint(ASTContext &Context,
const CXXRecordDecl *Src,
const CXXRecordDecl *Dst) {
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/false);
// If Dst is not derived from Src we can skip the whole computation below and
// return that Src is not a public base of Dst. Record all inheritance paths.
if (!Dst->isDerivedFrom(Src, Paths))
return CharUnits::fromQuantity(-2ULL);
unsigned NumPublicPaths = 0;
CharUnits Offset;
// Now walk all possible inheritance paths.
for (CXXBasePaths::paths_iterator I = Paths.begin(), E = Paths.end(); I != E;
++I) {
if (I->Access != AS_public) // Ignore non-public inheritance.
continue;
++NumPublicPaths;
for (CXXBasePath::iterator J = I->begin(), JE = I->end(); J != JE; ++J) {
// If the path contains a virtual base class we can't give any hint.
// -1: no hint.
if (J->Base->isVirtual())
return CharUnits::fromQuantity(-1ULL);
if (NumPublicPaths > 1) // Won't use offsets, skip computation.
continue;
// Accumulate the base class offsets.
const ASTRecordLayout &L = Context.getASTRecordLayout(J->Class);
Offset += L.getBaseClassOffset(J->Base->getType()->getAsCXXRecordDecl());
}
}
// -2: Src is not a public base of Dst.
if (NumPublicPaths == 0)
return CharUnits::fromQuantity(-2ULL);
// -3: Src is a multiple public base type but never a virtual base type.
if (NumPublicPaths > 1)
return CharUnits::fromQuantity(-3ULL);
// Otherwise, the Src type is a unique public nonvirtual base type of Dst.
// Return the offset of Src from the origin of Dst.
return Offset;
}
static llvm::Constant *getBadTypeidFn(CodeGenFunction &CGF) {
// void __cxa_bad_typeid();
llvm::FunctionType *FTy = llvm::FunctionType::get(CGF.VoidTy, false);
return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_bad_typeid");
}
bool ItaniumCXXABI::shouldTypeidBeNullChecked(bool IsDeref,
QualType SrcRecordTy) {
return IsDeref;
}
void ItaniumCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) {
llvm::Value *Fn = getBadTypeidFn(CGF);
CGF.EmitRuntimeCallOrInvoke(Fn).setDoesNotReturn();
CGF.Builder.CreateUnreachable();
}
llvm::Value *ItaniumCXXABI::EmitTypeid(CodeGenFunction &CGF,
QualType SrcRecordTy,
llvm::Value *ThisPtr,
llvm::Type *StdTypeInfoPtrTy) {
llvm::Value *Value =
CGF.GetVTablePtr(ThisPtr, StdTypeInfoPtrTy->getPointerTo());
// Load the type info.
Value = CGF.Builder.CreateConstInBoundsGEP1_64(Value, -1ULL);
return CGF.Builder.CreateLoad(Value);
}
bool ItaniumCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr,
QualType SrcRecordTy) {
return SrcIsPtr;
}
llvm::Value *ItaniumCXXABI::EmitDynamicCastCall(
CodeGenFunction &CGF, llvm::Value *Value, QualType SrcRecordTy,
QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) {
llvm::Type *PtrDiffLTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
llvm::Type *DestLTy = CGF.ConvertType(DestTy);
llvm::Value *SrcRTTI =
CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType());
llvm::Value *DestRTTI =
CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType());
// Compute the offset hint.
const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl();
const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl();
llvm::Value *OffsetHint = llvm::ConstantInt::get(
PtrDiffLTy,
computeOffsetHint(CGF.getContext(), SrcDecl, DestDecl).getQuantity());
// Emit the call to __dynamic_cast.
Value = CGF.EmitCastToVoidPtr(Value);
llvm::Value *args[] = {Value, SrcRTTI, DestRTTI, OffsetHint};
Value = CGF.EmitNounwindRuntimeCall(getItaniumDynamicCastFn(CGF), args);
Value = CGF.Builder.CreateBitCast(Value, DestLTy);
/// C++ [expr.dynamic.cast]p9:
/// A failed cast to reference type throws std::bad_cast
if (DestTy->isReferenceType()) {
llvm::BasicBlock *BadCastBlock =
CGF.createBasicBlock("dynamic_cast.bad_cast");
llvm::Value *IsNull = CGF.Builder.CreateIsNull(Value);
CGF.Builder.CreateCondBr(IsNull, BadCastBlock, CastEnd);
CGF.EmitBlock(BadCastBlock);
EmitBadCastCall(CGF);
}
return Value;
}
llvm::Value *ItaniumCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF,
llvm::Value *Value,
QualType SrcRecordTy,
QualType DestTy) {
llvm::Type *PtrDiffLTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
llvm::Type *DestLTy = CGF.ConvertType(DestTy);
// Get the vtable pointer.
llvm::Value *VTable = CGF.GetVTablePtr(Value, PtrDiffLTy->getPointerTo());
// Get the offset-to-top from the vtable.
llvm::Value *OffsetToTop =
CGF.Builder.CreateConstInBoundsGEP1_64(VTable, -2ULL);
OffsetToTop = CGF.Builder.CreateLoad(OffsetToTop, "offset.to.top");
// Finally, add the offset to the pointer.
Value = CGF.EmitCastToVoidPtr(Value);
Value = CGF.Builder.CreateInBoundsGEP(Value, OffsetToTop);
return CGF.Builder.CreateBitCast(Value, DestLTy);
}
bool ItaniumCXXABI::EmitBadCastCall(CodeGenFunction &CGF) {
llvm::Value *Fn = getBadCastFn(CGF);
CGF.EmitRuntimeCallOrInvoke(Fn).setDoesNotReturn();
CGF.Builder.CreateUnreachable();
return true;
}
llvm::Value *
ItaniumCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF,
llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
llvm::Value *VTablePtr = CGF.GetVTablePtr(This, CGM.Int8PtrTy);
CharUnits VBaseOffsetOffset =
CGM.getItaniumVTableContext().getVirtualBaseOffsetOffset(ClassDecl,
BaseClassDecl);
llvm::Value *VBaseOffsetPtr =
CGF.Builder.CreateConstGEP1_64(VTablePtr, VBaseOffsetOffset.getQuantity(),
"vbase.offset.ptr");
VBaseOffsetPtr = CGF.Builder.CreateBitCast(VBaseOffsetPtr,
CGM.PtrDiffTy->getPointerTo());
llvm::Value *VBaseOffset =
CGF.Builder.CreateLoad(VBaseOffsetPtr, "vbase.offset");
return VBaseOffset;
}
void ItaniumCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
// Just make sure we're in sync with TargetCXXABI.
assert(CGM.getTarget().getCXXABI().hasConstructorVariants());
// The constructor used for constructing this as a base class;
// ignores virtual bases.
CGM.EmitGlobal(GlobalDecl(D, Ctor_Base));
// The constructor used for constructing this as a complete class;
// constructs the virtual bases, then calls the base constructor.
if (!D->getParent()->isAbstract()) {
// We don't need to emit the complete ctor if the class is abstract.
CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete));
}
}
void
ItaniumCXXABI::buildStructorSignature(const CXXMethodDecl *MD, StructorType T,
SmallVectorImpl<CanQualType> &ArgTys) {
ASTContext &Context = getContext();
// All parameters are already in place except VTT, which goes after 'this'.
// These are Clang types, so we don't need to worry about sret yet.
// Check if we need to add a VTT parameter (which has type void **).
if (T == StructorType::Base && MD->getParent()->getNumVBases() != 0)
ArgTys.insert(ArgTys.begin() + 1,
Context.getPointerType(Context.VoidPtrTy));
}
void ItaniumCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
// The destructor used for destructing this as a base class; ignores
// virtual bases.
CGM.EmitGlobal(GlobalDecl(D, Dtor_Base));
// The destructor used for destructing this as a most-derived class;
// call the base destructor and then destructs any virtual bases.
CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete));
// The destructor in a virtual table is always a 'deleting'
// destructor, which calls the complete destructor and then uses the
// appropriate operator delete.
if (D->isVirtual())
CGM.EmitGlobal(GlobalDecl(D, Dtor_Deleting));
}
void ItaniumCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
QualType &ResTy,
FunctionArgList &Params) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
// Check if we need a VTT parameter as well.
if (NeedsVTTParameter(CGF.CurGD)) {
ASTContext &Context = getContext();
// FIXME: avoid the fake decl
QualType T = Context.getPointerType(Context.VoidPtrTy);
ImplicitParamDecl *VTTDecl
= ImplicitParamDecl::Create(Context, nullptr, MD->getLocation(),
&Context.Idents.get("vtt"), T);
Params.insert(Params.begin() + 1, VTTDecl);
getStructorImplicitParamDecl(CGF) = VTTDecl;
}
}
void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
/// Initialize the 'this' slot.
EmitThisParam(CGF);
/// Initialize the 'vtt' slot if needed.
if (getStructorImplicitParamDecl(CGF)) {
getStructorImplicitParamValue(CGF) = CGF.Builder.CreateLoad(
CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), "vtt");
}
/// If this is a function that the ABI specifies returns 'this', initialize
/// the return slot to 'this' at the start of the function.
///
/// Unlike the setting of return types, this is done within the ABI
/// implementation instead of by clients of CGCXXABI because:
/// 1) getThisValue is currently protected
/// 2) in theory, an ABI could implement 'this' returns some other way;
/// HasThisReturn only specifies a contract, not the implementation
if (HasThisReturn(CGF.CurGD))
CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
}
unsigned ItaniumCXXABI::addImplicitConstructorArgs(
CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
bool ForVirtualBase, bool Delegating, CallArgList &Args) {
if (!NeedsVTTParameter(GlobalDecl(D, Type)))
return 0;
// Insert the implicit 'vtt' argument as the second argument.
llvm::Value *VTT =
CGF.GetVTTParameter(GlobalDecl(D, Type), ForVirtualBase, Delegating);
QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy);
Args.insert(Args.begin() + 1,
CallArg(RValue::get(VTT), VTTTy, /*needscopy=*/false));
return 1; // Added one arg.
}
void ItaniumCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
const CXXDestructorDecl *DD,
CXXDtorType Type, bool ForVirtualBase,
bool Delegating, llvm::Value *This) {
GlobalDecl GD(DD, Type);
llvm::Value *VTT = CGF.GetVTTParameter(GD, ForVirtualBase, Delegating);
QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy);
llvm::Value *Callee = nullptr;
if (getContext().getLangOpts().AppleKext)
Callee = CGF.BuildAppleKextVirtualDestructorCall(DD, Type, DD->getParent());
if (!Callee)
Callee = CGM.getAddrOfCXXStructor(DD, getFromDtorType(Type));
CGF.EmitCXXMemberOrOperatorCall(DD, Callee, ReturnValueSlot(), This, VTT,
VTTTy, nullptr);
}
void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
const CXXRecordDecl *RD) {
llvm::GlobalVariable *VTable = getAddrOfVTable(RD, CharUnits());
if (VTable->hasInitializer())
return;
ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext();
const VTableLayout &VTLayout = VTContext.getVTableLayout(RD);
llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD);
llvm::Constant *RTTI =
CGM.GetAddrOfRTTIDescriptor(CGM.getContext().getTagDeclType(RD));
// Create and set the initializer.
llvm::Constant *Init = CGVT.CreateVTableInitializer(
RD, VTLayout.vtable_component_begin(), VTLayout.getNumVTableComponents(),
VTLayout.vtable_thunk_begin(), VTLayout.getNumVTableThunks(), RTTI);
VTable->setInitializer(Init);
// Set the correct linkage.
VTable->setLinkage(Linkage);
if (CGM.supportsCOMDAT() && VTable->isWeakForLinker())
VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName()));
// Set the right visibility.
CGM.setGlobalVisibility(VTable, RD);
// Use pointer alignment for the vtable. Otherwise we would align them based
// on the size of the initializer which doesn't make sense as only single
// values are read.
unsigned PAlign = CGM.getTarget().getPointerAlign(0);
VTable->setAlignment(getContext().toCharUnitsFromBits(PAlign).getQuantity());
// If this is the magic class __cxxabiv1::__fundamental_type_info,
// we will emit the typeinfo for the fundamental types. This is the
// same behaviour as GCC.
const DeclContext *DC = RD->getDeclContext();
if (RD->getIdentifier() &&
RD->getIdentifier()->isStr("__fundamental_type_info") &&
isa<NamespaceDecl>(DC) && cast<NamespaceDecl>(DC)->getIdentifier() &&
cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") &&
DC->getParent()->isTranslationUnit())
EmitFundamentalRTTIDescriptors();
}
llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor(
CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base,
const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) {
bool NeedsVTTParam = CGM.getCXXABI().NeedsVTTParameter(CGF.CurGD);
NeedsVirtualOffset = (NeedsVTTParam && NearestVBase);
llvm::Value *VTableAddressPoint;
if (NeedsVTTParam && (Base.getBase()->getNumVBases() || NearestVBase)) {
// Get the secondary vpointer index.
uint64_t VirtualPointerIndex =
CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);
/// Load the VTT.
llvm::Value *VTT = CGF.LoadCXXVTT();
if (VirtualPointerIndex)
VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex);
// And load the address point from the VTT.
VTableAddressPoint = CGF.Builder.CreateLoad(VTT);
} else {
llvm::Constant *VTable =
CGM.getCXXABI().getAddrOfVTable(VTableClass, CharUnits());
uint64_t AddressPoint = CGM.getItaniumVTableContext()
.getVTableLayout(VTableClass)
.getAddressPoint(Base);
VTableAddressPoint =
CGF.Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
}
return VTableAddressPoint;
}
llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr(
BaseSubobject Base, const CXXRecordDecl *VTableClass) {
llvm::Constant *VTable = getAddrOfVTable(VTableClass, CharUnits());
// Find the appropriate vtable within the vtable group.
uint64_t AddressPoint = CGM.getItaniumVTableContext()
.getVTableLayout(VTableClass)
.getAddressPoint(Base);
llvm::Value *Indices[] = {
llvm::ConstantInt::get(CGM.Int64Ty, 0),
llvm::ConstantInt::get(CGM.Int64Ty, AddressPoint)
};
return llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Indices);
}
llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
CharUnits VPtrOffset) {
assert(VPtrOffset.isZero() && "Itanium ABI only supports zero vptr offsets");
llvm::GlobalVariable *&VTable = VTables[RD];
if (VTable)
return VTable;
// Queue up this v-table for possible deferred emission.
CGM.addDeferredVTable(RD);
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
getMangleContext().mangleCXXVTable(RD, Out);
Out.flush();
StringRef Name = OutName.str();
ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext();
llvm::ArrayType *ArrayType = llvm::ArrayType::get(
CGM.Int8PtrTy, VTContext.getVTableLayout(RD).getNumVTableComponents());
VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
Name, ArrayType, llvm::GlobalValue::ExternalLinkage);
VTable->setUnnamedAddr(true);
if (RD->hasAttr<DLLImportAttr>())
VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
else if (RD->hasAttr<DLLExportAttr>())
VTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
return VTable;
}
llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
GlobalDecl GD,
llvm::Value *This,
llvm::Type *Ty) {
GD = GD.getCanonicalDecl();
Ty = Ty->getPointerTo()->getPointerTo();
llvm::Value *VTable = CGF.GetVTablePtr(This, Ty);
uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD);
llvm::Value *VFuncPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn");
return CGF.Builder.CreateLoad(VFuncPtr);
}
llvm::Value *ItaniumCXXABI::EmitVirtualDestructorCall(
CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType,
llvm::Value *This, const CXXMemberCallExpr *CE) {
assert(CE == nullptr || CE->arg_begin() == CE->arg_end());
assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete);
const CGFunctionInfo *FInfo = &CGM.getTypes().arrangeCXXStructorDeclaration(
Dtor, getFromDtorType(DtorType));
llvm::Type *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo);
llvm::Value *Callee =
getVirtualFunctionPointer(CGF, GlobalDecl(Dtor, DtorType), This, Ty);
CGF.EmitCXXMemberOrOperatorCall(Dtor, Callee, ReturnValueSlot(), This,
/*ImplicitParam=*/nullptr, QualType(), CE);
return nullptr;
}
void ItaniumCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) {
CodeGenVTables &VTables = CGM.getVTables();
llvm::GlobalVariable *VTT = VTables.GetAddrOfVTT(RD);
VTables.EmitVTTDefinition(VTT, CGM.getVTableLinkage(RD), RD);
}
static llvm::Value *performTypeAdjustment(CodeGenFunction &CGF,
llvm::Value *Ptr,
int64_t NonVirtualAdjustment,
int64_t VirtualAdjustment,
bool IsReturnAdjustment) {
if (!NonVirtualAdjustment && !VirtualAdjustment)
return Ptr;
llvm::Type *Int8PtrTy = CGF.Int8PtrTy;
llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy);
if (NonVirtualAdjustment && !IsReturnAdjustment) {
// Perform the non-virtual adjustment for a base-to-derived cast.
V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
}
if (VirtualAdjustment) {
llvm::Type *PtrDiffTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
// Perform the virtual adjustment.
llvm::Value *VTablePtrPtr =
CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo());
llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr);
llvm::Value *OffsetPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment);
OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo());
// Load the adjustment offset from the vtable.
llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr);
// Adjust our pointer.
V = CGF.Builder.CreateInBoundsGEP(V, Offset);
}
if (NonVirtualAdjustment && IsReturnAdjustment) {
// Perform the non-virtual adjustment for a derived-to-base cast.
V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
}
// Cast back to the original type.
return CGF.Builder.CreateBitCast(V, Ptr->getType());
}
llvm::Value *ItaniumCXXABI::performThisAdjustment(CodeGenFunction &CGF,
llvm::Value *This,
const ThisAdjustment &TA) {
return performTypeAdjustment(CGF, This, TA.NonVirtual,
TA.Virtual.Itanium.VCallOffsetOffset,
/*IsReturnAdjustment=*/false);
}
llvm::Value *
ItaniumCXXABI::performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret,
const ReturnAdjustment &RA) {
return performTypeAdjustment(CGF, Ret, RA.NonVirtual,
RA.Virtual.Itanium.VBaseOffsetOffset,
/*IsReturnAdjustment=*/true);
}
void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
RValue RV, QualType ResultType) {
if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl()))
return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType);
// Destructor thunks in the ARM ABI have indeterminate results.
llvm::Type *T =
cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType();
RValue Undef = RValue::get(llvm::UndefValue::get(T));
return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType);
}
/************************** Array allocation cookies **************************/
CharUnits ItaniumCXXABI::getArrayCookieSizeImpl(QualType elementType) {
// The array cookie is a size_t; pad that up to the element alignment.
// The cookie is actually right-justified in that space.
return std::max(CharUnits::fromQuantity(CGM.SizeSizeInBytes),
CGM.getContext().getTypeAlignInChars(elementType));
}
llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *NewPtr,
llvm::Value *NumElements,
const CXXNewExpr *expr,
QualType ElementType) {
assert(requiresArrayCookie(expr));
unsigned AS = NewPtr->getType()->getPointerAddressSpace();
ASTContext &Ctx = getContext();
QualType SizeTy = Ctx.getSizeType();
CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy);
// The size of the cookie.
CharUnits CookieSize =
std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType));
assert(CookieSize == getArrayCookieSizeImpl(ElementType));
// Compute an offset to the cookie.
llvm::Value *CookiePtr = NewPtr;
CharUnits CookieOffset = CookieSize - SizeSize;
if (!CookieOffset.isZero())
CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr,
CookieOffset.getQuantity());
// Write the number of elements into the appropriate slot.
llvm::Type *NumElementsTy = CGF.ConvertType(SizeTy)->getPointerTo(AS);
llvm::Value *NumElementsPtr =
CGF.Builder.CreateBitCast(CookiePtr, NumElementsTy);
llvm::Instruction *SI = CGF.Builder.CreateStore(NumElements, NumElementsPtr);
if (CGM.getLangOpts().Sanitize.has(SanitizerKind::Address) && AS == 0 &&
expr->getOperatorNew()->isReplaceableGlobalAllocationFunction()) {
// The store to the CookiePtr does not need to be instrumented.
CGM.getSanitizerMetadata()->disableSanitizerForInstruction(SI);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, NumElementsTy, false);
llvm::Constant *F =
CGM.CreateRuntimeFunction(FTy, "__asan_poison_cxx_array_cookie");
CGF.Builder.CreateCall(F, NumElementsPtr);
}
// Finally, compute a pointer to the actual data buffer by skipping
// over the cookie completely.
return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr,
CookieSize.getQuantity());
}
llvm::Value *ItaniumCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize) {
// The element size is right-justified in the cookie.
llvm::Value *numElementsPtr = allocPtr;
CharUnits numElementsOffset =
cookieSize - CharUnits::fromQuantity(CGF.SizeSizeInBytes);
if (!numElementsOffset.isZero())
numElementsPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(numElementsPtr,
numElementsOffset.getQuantity());
unsigned AS = allocPtr->getType()->getPointerAddressSpace();
numElementsPtr =
CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS));
if (!CGM.getLangOpts().Sanitize.has(SanitizerKind::Address) || AS != 0)
return CGF.Builder.CreateLoad(numElementsPtr);
// In asan mode emit a function call instead of a regular load and let the
// run-time deal with it: if the shadow is properly poisoned return the
// cookie, otherwise return 0 to avoid an infinite loop calling DTORs.
// We can't simply ignore this load using nosanitize metadata because
// the metadata may be lost.
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGF.SizeTy, CGF.SizeTy->getPointerTo(0), false);
llvm::Constant *F =
CGM.CreateRuntimeFunction(FTy, "__asan_load_cxx_array_cookie");
return CGF.Builder.CreateCall(F, numElementsPtr);
}
CharUnits ARMCXXABI::getArrayCookieSizeImpl(QualType elementType) {
// ARM says that the cookie is always:
// struct array_cookie {
// std::size_t element_size; // element_size != 0
// std::size_t element_count;
// };
// But the base ABI doesn't give anything an alignment greater than
// 8, so we can dismiss this as typical ABI-author blindness to
// actual language complexity and round up to the element alignment.
return std::max(CharUnits::fromQuantity(2 * CGM.SizeSizeInBytes),
CGM.getContext().getTypeAlignInChars(elementType));
}
llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
llvm::Value *newPtr,
llvm::Value *numElements,
const CXXNewExpr *expr,
QualType elementType) {
assert(requiresArrayCookie(expr));
// NewPtr is a char*, but we generalize to arbitrary addrspaces.
unsigned AS = newPtr->getType()->getPointerAddressSpace();
// The cookie is always at the start of the buffer.
llvm::Value *cookie = newPtr;
// The first element is the element size.
cookie = CGF.Builder.CreateBitCast(cookie, CGF.SizeTy->getPointerTo(AS));
llvm::Value *elementSize = llvm::ConstantInt::get(CGF.SizeTy,
getContext().getTypeSizeInChars(elementType).getQuantity());
CGF.Builder.CreateStore(elementSize, cookie);
// The second element is the element count.
cookie = CGF.Builder.CreateConstInBoundsGEP1_32(cookie, 1);
CGF.Builder.CreateStore(numElements, cookie);
// Finally, compute a pointer to the actual data buffer by skipping
// over the cookie completely.
CharUnits cookieSize = ARMCXXABI::getArrayCookieSizeImpl(elementType);
return CGF.Builder.CreateConstInBoundsGEP1_64(newPtr,
cookieSize.getQuantity());
}
llvm::Value *ARMCXXABI::readArrayCookieImpl(CodeGenFunction &CGF,
llvm::Value *allocPtr,
CharUnits cookieSize) {
// The number of elements is at offset sizeof(size_t) relative to
// the allocated pointer.
llvm::Value *numElementsPtr
= CGF.Builder.CreateConstInBoundsGEP1_64(allocPtr, CGF.SizeSizeInBytes);
unsigned AS = allocPtr->getType()->getPointerAddressSpace();
numElementsPtr =
CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS));
return CGF.Builder.CreateLoad(numElementsPtr);
}
/*********************** Static local initialization **************************/
static llvm::Constant *getGuardAcquireFn(CodeGenModule &CGM,
llvm::PointerType *GuardPtrTy) {
// int __cxa_guard_acquire(__guard *guard_object);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy),
GuardPtrTy, /*isVarArg=*/false);
return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire",
llvm::AttributeSet::get(CGM.getLLVMContext(),
llvm::AttributeSet::FunctionIndex,
llvm::Attribute::NoUnwind));
}
static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM,
llvm::PointerType *GuardPtrTy) {
// void __cxa_guard_release(__guard *guard_object);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false);
return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release",
llvm::AttributeSet::get(CGM.getLLVMContext(),
llvm::AttributeSet::FunctionIndex,
llvm::Attribute::NoUnwind));
}
static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM,
llvm::PointerType *GuardPtrTy) {
// void __cxa_guard_abort(__guard *guard_object);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, GuardPtrTy, /*isVarArg=*/false);
return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort",
llvm::AttributeSet::get(CGM.getLLVMContext(),
llvm::AttributeSet::FunctionIndex,
llvm::Attribute::NoUnwind));
}
namespace {
struct CallGuardAbort : EHScopeStack::Cleanup {
llvm::GlobalVariable *Guard;
CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.EmitNounwindRuntimeCall(getGuardAbortFn(CGF.CGM, Guard->getType()),
Guard);
}
};
}
/// The ARM code here follows the Itanium code closely enough that we
/// just special-case it at particular places.
void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
const VarDecl &D,
llvm::GlobalVariable *var,
bool shouldPerformInit) {
CGBuilderTy &Builder = CGF.Builder;
// We only need to use thread-safe statics for local non-TLS variables;
// global initialization is always single-threaded.
bool threadsafe = getContext().getLangOpts().ThreadsafeStatics &&
D.isLocalVarDecl() && !D.getTLSKind();
// If we have a global variable with internal linkage and thread-safe statics
// are disabled, we can just let the guard variable be of type i8.
bool useInt8GuardVariable = !threadsafe && var->hasInternalLinkage();
llvm::IntegerType *guardTy;
if (useInt8GuardVariable) {
guardTy = CGF.Int8Ty;
} else {
// Guard variables are 64 bits in the generic ABI and size width on ARM
// (i.e. 32-bit on AArch32, 64-bit on AArch64).
guardTy = (UseARMGuardVarABI ? CGF.SizeTy : CGF.Int64Ty);
}
llvm::PointerType *guardPtrTy = guardTy->getPointerTo();
// Create the guard variable if we don't already have it (as we
// might if we're double-emitting this function body).
llvm::GlobalVariable *guard = CGM.getStaticLocalDeclGuardAddress(&D);
if (!guard) {
// Mangle the name for the guard.
SmallString<256> guardName;
{
llvm::raw_svector_ostream out(guardName);
getMangleContext().mangleStaticGuardVariable(&D, out);
out.flush();
}
// Create the guard variable with a zero-initializer.
// Just absorb linkage and visibility from the guarded variable.
guard = new llvm::GlobalVariable(CGM.getModule(), guardTy,
false, var->getLinkage(),
llvm::ConstantInt::get(guardTy, 0),
guardName.str());
guard->setVisibility(var->getVisibility());
// If the variable is thread-local, so is its guard variable.
guard->setThreadLocalMode(var->getThreadLocalMode());
// The ABI says: It is suggested that it be emitted in the same COMDAT group
// as the associated data object
llvm::Comdat *C = var->getComdat();
if (!D.isLocalVarDecl() && C) {
guard->setComdat(C);
CGF.CurFn->setComdat(C);
} else if (CGM.supportsCOMDAT() && guard->isWeakForLinker()) {
guard->setComdat(CGM.getModule().getOrInsertComdat(guard->getName()));
}
CGM.setStaticLocalDeclGuardAddress(&D, guard);
}
// Test whether the variable has completed initialization.
//
// Itanium C++ ABI 3.3.2:
// The following is pseudo-code showing how these functions can be used:
// if (obj_guard.first_byte == 0) {
// if ( __cxa_guard_acquire (&obj_guard) ) {
// try {
// ... initialize the object ...;
// } catch (...) {
// __cxa_guard_abort (&obj_guard);
// throw;
// }
// ... queue object destructor with __cxa_atexit() ...;
// __cxa_guard_release (&obj_guard);
// }
// }
// Load the first byte of the guard variable.
llvm::LoadInst *LI =
Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy));
LI->setAlignment(1);
// Itanium ABI:
// An implementation supporting thread-safety on multiprocessor
// systems must also guarantee that references to the initialized
// object do not occur before the load of the initialization flag.
//
// In LLVM, we do this by marking the load Acquire.
if (threadsafe)
LI->setAtomic(llvm::Acquire);
// For ARM, we should only check the first bit, rather than the entire byte:
//
// ARM C++ ABI 3.2.3.1:
// To support the potential use of initialization guard variables
// as semaphores that are the target of ARM SWP and LDREX/STREX
// synchronizing instructions we define a static initialization
// guard variable to be a 4-byte aligned, 4-byte word with the
// following inline access protocol.
// #define INITIALIZED 1
// if ((obj_guard & INITIALIZED) != INITIALIZED) {
// if (__cxa_guard_acquire(&obj_guard))
// ...
// }
//
// and similarly for ARM64:
//
// ARM64 C++ ABI 3.2.2:
// This ABI instead only specifies the value bit 0 of the static guard
// variable; all other bits are platform defined. Bit 0 shall be 0 when the
// variable is not initialized and 1 when it is.
llvm::Value *V =
(UseARMGuardVarABI && !useInt8GuardVariable)
? Builder.CreateAnd(LI, llvm::ConstantInt::get(CGM.Int8Ty, 1))
: LI;
llvm::Value *isInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check");
llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
// Check if the first byte of the guard variable is zero.
Builder.CreateCondBr(isInitialized, InitCheckBlock, EndBlock);
CGF.EmitBlock(InitCheckBlock);
// Variables used when coping with thread-safe statics and exceptions.
if (threadsafe) {
// Call __cxa_guard_acquire.
llvm::Value *V
= CGF.EmitNounwindRuntimeCall(getGuardAcquireFn(CGM, guardPtrTy), guard);
llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
InitBlock, EndBlock);
// Call __cxa_guard_abort along the exceptional edge.
CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, guard);
CGF.EmitBlock(InitBlock);
}
// Emit the initializer and add a global destructor if appropriate.
CGF.EmitCXXGlobalVarDeclInit(D, var, shouldPerformInit);
if (threadsafe) {
// Pop the guard-abort cleanup if we pushed one.
CGF.PopCleanupBlock();
// Call __cxa_guard_release. This cannot throw.
CGF.EmitNounwindRuntimeCall(getGuardReleaseFn(CGM, guardPtrTy), guard);
} else {
Builder.CreateStore(llvm::ConstantInt::get(guardTy, 1), guard);
}
CGF.EmitBlock(EndBlock);
}
/// Register a global destructor using __cxa_atexit.
static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF,
llvm::Constant *dtor,
llvm::Constant *addr,
bool TLS) {
const char *Name = "__cxa_atexit";
if (TLS) {
const llvm::Triple &T = CGF.getTarget().getTriple();
Name = T.isMacOSX() ? "_tlv_atexit" : "__cxa_thread_atexit";
}
// We're assuming that the destructor function is something we can
// reasonably call with the default CC. Go ahead and cast it to the
// right prototype.
llvm::Type *dtorTy =
llvm::FunctionType::get(CGF.VoidTy, CGF.Int8PtrTy, false)->getPointerTo();
// extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d);
llvm::Type *paramTys[] = { dtorTy, CGF.Int8PtrTy, CGF.Int8PtrTy };
llvm::FunctionType *atexitTy =
llvm::FunctionType::get(CGF.IntTy, paramTys, false);
// Fetch the actual function.
llvm::Constant *atexit = CGF.CGM.CreateRuntimeFunction(atexitTy, Name);
if (llvm::Function *fn = dyn_cast<llvm::Function>(atexit))
fn->setDoesNotThrow();
// Create a variable that binds the atexit to this shared object.
llvm::Constant *handle =
CGF.CGM.CreateRuntimeVariable(CGF.Int8Ty, "__dso_handle");
llvm::Value *args[] = {
llvm::ConstantExpr::getBitCast(dtor, dtorTy),
llvm::ConstantExpr::getBitCast(addr, CGF.Int8PtrTy),
handle
};
CGF.EmitNounwindRuntimeCall(atexit, args);
}
/// Register a global destructor as best as we know how.
void ItaniumCXXABI::registerGlobalDtor(CodeGenFunction &CGF,
const VarDecl &D,
llvm::Constant *dtor,
llvm::Constant *addr) {
// Use __cxa_atexit if available.
if (CGM.getCodeGenOpts().CXAAtExit)
return emitGlobalDtorWithCXAAtExit(CGF, dtor, addr, D.getTLSKind());
if (D.getTLSKind())
CGM.ErrorUnsupported(&D, "non-trivial TLS destruction");
// In Apple kexts, we want to add a global destructor entry.
// FIXME: shouldn't this be guarded by some variable?
if (CGM.getLangOpts().AppleKext) {
// Generate a global destructor entry.
return CGM.AddCXXDtorEntry(dtor, addr);
}
CGF.registerGlobalDtorWithAtExit(D, dtor, addr);
}
static bool isThreadWrapperReplaceable(const VarDecl *VD,
CodeGen::CodeGenModule &CGM) {
assert(!VD->isStaticLocal() && "static local VarDecls don't need wrappers!");
// OS X prefers to have references to thread local variables to go through
// the thread wrapper instead of directly referencing the backing variable.
return VD->getTLSKind() == VarDecl::TLS_Dynamic &&
CGM.getTarget().getTriple().isMacOSX();
}
/// Get the appropriate linkage for the wrapper function. This is essentially
/// the weak form of the variable's linkage; every translation unit which needs
/// the wrapper emits a copy, and we want the linker to merge them.
static llvm::GlobalValue::LinkageTypes
getThreadLocalWrapperLinkage(const VarDecl *VD, CodeGen::CodeGenModule &CGM) {
llvm::GlobalValue::LinkageTypes VarLinkage =
CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false);
// For internal linkage variables, we don't need an external or weak wrapper.
if (llvm::GlobalValue::isLocalLinkage(VarLinkage))
return VarLinkage;
// If the thread wrapper is replaceable, give it appropriate linkage.
if (isThreadWrapperReplaceable(VD, CGM)) {
if (llvm::GlobalVariable::isLinkOnceLinkage(VarLinkage) ||
llvm::GlobalVariable::isWeakODRLinkage(VarLinkage))
return llvm::GlobalVariable::WeakAnyLinkage;
return VarLinkage;
}
return llvm::GlobalValue::WeakODRLinkage;
}
llvm::Function *
ItaniumCXXABI::getOrCreateThreadLocalWrapper(const VarDecl *VD,
llvm::Value *Val) {
// Mangle the name for the thread_local wrapper function.
SmallString<256> WrapperName;
{
llvm::raw_svector_ostream Out(WrapperName);
getMangleContext().mangleItaniumThreadLocalWrapper(VD, Out);
Out.flush();
}
if (llvm::Value *V = CGM.getModule().getNamedValue(WrapperName))
return cast<llvm::Function>(V);
llvm::Type *RetTy = Val->getType();
if (VD->getType()->isReferenceType())
RetTy = RetTy->getPointerElementType();
llvm::FunctionType *FnTy = llvm::FunctionType::get(RetTy, false);
llvm::Function *Wrapper =
llvm::Function::Create(FnTy, getThreadLocalWrapperLinkage(VD, CGM),
WrapperName.str(), &CGM.getModule());
// Always resolve references to the wrapper at link time.
if (!Wrapper->hasLocalLinkage() && !isThreadWrapperReplaceable(VD, CGM))
Wrapper->setVisibility(llvm::GlobalValue::HiddenVisibility);
return Wrapper;
}
void ItaniumCXXABI::EmitThreadLocalInitFuncs(
CodeGenModule &CGM,
ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *>>
CXXThreadLocals, ArrayRef<llvm::Function *> CXXThreadLocalInits,
ArrayRef<llvm::GlobalVariable *> CXXThreadLocalInitVars) {
llvm::Function *InitFunc = nullptr;
if (!CXXThreadLocalInits.empty()) {
// Generate a guarded initialization function.
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
InitFunc = CGM.CreateGlobalInitOrDestructFunction(FTy, "__tls_init",
SourceLocation(),
/*TLS=*/true);
llvm::GlobalVariable *Guard = new llvm::GlobalVariable(
CGM.getModule(), CGM.Int8Ty, /*isConstant=*/false,
llvm::GlobalVariable::InternalLinkage,
llvm::ConstantInt::get(CGM.Int8Ty, 0), "__tls_guard");
Guard->setThreadLocal(true);
CodeGenFunction(CGM)
.GenerateCXXGlobalInitFunc(InitFunc, CXXThreadLocalInits, Guard);
}
for (unsigned I = 0, N = CXXThreadLocals.size(); I != N; ++I) {
const VarDecl *VD = CXXThreadLocals[I].first;
llvm::GlobalVariable *Var = CXXThreadLocals[I].second;
// Some targets require that all access to thread local variables go through
// the thread wrapper. This means that we cannot attempt to create a thread
// wrapper or a thread helper.
if (isThreadWrapperReplaceable(VD, CGM) && !VD->hasDefinition())
continue;
// Mangle the name for the thread_local initialization function.
SmallString<256> InitFnName;
{
llvm::raw_svector_ostream Out(InitFnName);
getMangleContext().mangleItaniumThreadLocalInit(VD, Out);
Out.flush();
}
// If we have a definition for the variable, emit the initialization
// function as an alias to the global Init function (if any). Otherwise,
// produce a declaration of the initialization function.
llvm::GlobalValue *Init = nullptr;
bool InitIsInitFunc = false;
if (VD->hasDefinition()) {
InitIsInitFunc = true;
if (InitFunc)
Init = llvm::GlobalAlias::create(Var->getLinkage(), InitFnName.str(),
InitFunc);
} else {
// Emit a weak global function referring to the initialization function.
// This function will not exist if the TU defining the thread_local
// variable in question does not need any dynamic initialization for
// its thread_local variables.
llvm::FunctionType *FnTy = llvm::FunctionType::get(CGM.VoidTy, false);
Init = llvm::Function::Create(
FnTy, llvm::GlobalVariable::ExternalWeakLinkage, InitFnName.str(),
&CGM.getModule());
}
if (Init)
Init->setVisibility(Var->getVisibility());
llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Var);
llvm::LLVMContext &Context = CGM.getModule().getContext();
llvm::BasicBlock *Entry = llvm::BasicBlock::Create(Context, "", Wrapper);
CGBuilderTy Builder(Entry);
if (InitIsInitFunc) {
if (Init)
Builder.CreateCall(Init);
} else {
// Don't know whether we have an init function. Call it if it exists.
llvm::Value *Have = Builder.CreateIsNotNull(Init);
llvm::BasicBlock *InitBB = llvm::BasicBlock::Create(Context, "", Wrapper);
llvm::BasicBlock *ExitBB = llvm::BasicBlock::Create(Context, "", Wrapper);
Builder.CreateCondBr(Have, InitBB, ExitBB);
Builder.SetInsertPoint(InitBB);
Builder.CreateCall(Init);
Builder.CreateBr(ExitBB);
Builder.SetInsertPoint(ExitBB);
}
// For a reference, the result of the wrapper function is a pointer to
// the referenced object.
llvm::Value *Val = Var;
if (VD->getType()->isReferenceType()) {
llvm::LoadInst *LI = Builder.CreateLoad(Val);
LI->setAlignment(CGM.getContext().getDeclAlign(VD).getQuantity());
Val = LI;
}
if (Val->getType() != Wrapper->getReturnType())
Val = Builder.CreatePointerBitCastOrAddrSpaceCast(
Val, Wrapper->getReturnType(), "");
Builder.CreateRet(Val);
}
}
LValue ItaniumCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF,
const VarDecl *VD,
QualType LValType) {
QualType T = VD->getType();
llvm::Type *Ty = CGF.getTypes().ConvertTypeForMem(T);
llvm::Value *Val = CGF.CGM.GetAddrOfGlobalVar(VD, Ty);
llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Val);
Val = CGF.Builder.CreateCall(Wrapper);
LValue LV;
if (VD->getType()->isReferenceType())
LV = CGF.MakeNaturalAlignAddrLValue(Val, LValType);
else
LV = CGF.MakeAddrLValue(Val, LValType, CGF.getContext().getDeclAlign(VD));
// FIXME: need setObjCGCLValueClass?
return LV;
}
/// Return whether the given global decl needs a VTT parameter, which it does
/// if it's a base constructor or destructor with virtual bases.
bool ItaniumCXXABI::NeedsVTTParameter(GlobalDecl GD) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
// We don't have any virtual bases, just return early.
if (!MD->getParent()->getNumVBases())
return false;
// Check if we have a base constructor.
if (isa<CXXConstructorDecl>(MD) && GD.getCtorType() == Ctor_Base)
return true;
// Check if we have a base destructor.
if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
return true;
return false;
}
namespace {
class ItaniumRTTIBuilder {
CodeGenModule &CGM; // Per-module state.
llvm::LLVMContext &VMContext;
const ItaniumCXXABI &CXXABI; // Per-module state.
/// Fields - The fields of the RTTI descriptor currently being built.
SmallVector<llvm::Constant *, 16> Fields;
/// GetAddrOfTypeName - Returns the mangled type name of the given type.
llvm::GlobalVariable *
GetAddrOfTypeName(QualType Ty, llvm::GlobalVariable::LinkageTypes Linkage);
/// GetAddrOfExternalRTTIDescriptor - Returns the constant for the RTTI
/// descriptor of the given type.
llvm::Constant *GetAddrOfExternalRTTIDescriptor(QualType Ty);
/// BuildVTablePointer - Build the vtable pointer for the given type.
void BuildVTablePointer(const Type *Ty);
/// BuildSIClassTypeInfo - Build an abi::__si_class_type_info, used for single
/// inheritance, according to the Itanium C++ ABI, 2.9.5p6b.
void BuildSIClassTypeInfo(const CXXRecordDecl *RD);
/// BuildVMIClassTypeInfo - Build an abi::__vmi_class_type_info, used for
/// classes with bases that do not satisfy the abi::__si_class_type_info
/// constraints, according ti the Itanium C++ ABI, 2.9.5p5c.
void BuildVMIClassTypeInfo(const CXXRecordDecl *RD);
/// BuildPointerTypeInfo - Build an abi::__pointer_type_info struct, used
/// for pointer types.
void BuildPointerTypeInfo(QualType PointeeTy);
/// BuildObjCObjectTypeInfo - Build the appropriate kind of
/// type_info for an object type.
void BuildObjCObjectTypeInfo(const ObjCObjectType *Ty);
/// BuildPointerToMemberTypeInfo - Build an abi::__pointer_to_member_type_info
/// struct, used for member pointer types.
void BuildPointerToMemberTypeInfo(const MemberPointerType *Ty);
public:
ItaniumRTTIBuilder(const ItaniumCXXABI &ABI)
: CGM(ABI.CGM), VMContext(CGM.getModule().getContext()), CXXABI(ABI) {}
// Pointer type info flags.
enum {
/// PTI_Const - Type has const qualifier.
PTI_Const = 0x1,
/// PTI_Volatile - Type has volatile qualifier.
PTI_Volatile = 0x2,
/// PTI_Restrict - Type has restrict qualifier.
PTI_Restrict = 0x4,
/// PTI_Incomplete - Type is incomplete.
PTI_Incomplete = 0x8,
/// PTI_ContainingClassIncomplete - Containing class is incomplete.
/// (in pointer to member).
PTI_ContainingClassIncomplete = 0x10
};
// VMI type info flags.
enum {
/// VMI_NonDiamondRepeat - Class has non-diamond repeated inheritance.
VMI_NonDiamondRepeat = 0x1,
/// VMI_DiamondShaped - Class is diamond shaped.
VMI_DiamondShaped = 0x2
};
// Base class type info flags.
enum {
/// BCTI_Virtual - Base class is virtual.
BCTI_Virtual = 0x1,
/// BCTI_Public - Base class is public.
BCTI_Public = 0x2
};
/// BuildTypeInfo - Build the RTTI type info struct for the given type.
///
/// \param Force - true to force the creation of this RTTI value
llvm::Constant *BuildTypeInfo(QualType Ty, bool Force = false);
};
}
llvm::GlobalVariable *ItaniumRTTIBuilder::GetAddrOfTypeName(
QualType Ty, llvm::GlobalVariable::LinkageTypes Linkage) {
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().mangleCXXRTTIName(Ty, Out);
Out.flush();
StringRef Name = OutName.str();
// We know that the mangled name of the type starts at index 4 of the
// mangled name of the typename, so we can just index into it in order to
// get the mangled name of the type.
llvm::Constant *Init = llvm::ConstantDataArray::getString(VMContext,
Name.substr(4));
llvm::GlobalVariable *GV =
CGM.CreateOrReplaceCXXRuntimeVariable(Name, Init->getType(), Linkage);
GV->setInitializer(Init);
return GV;
}
llvm::Constant *
ItaniumRTTIBuilder::GetAddrOfExternalRTTIDescriptor(QualType Ty) {
// Mangle the RTTI name.
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
Out.flush();
StringRef Name = OutName.str();
// Look for an existing global.
llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name);
if (!GV) {
// Create a new global variable.
GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy,
/*Constant=*/true,
llvm::GlobalValue::ExternalLinkage, nullptr,
Name);
if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(RecordTy->getDecl());
if (RD->hasAttr<DLLImportAttr>())
GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
}
}
return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
}
/// TypeInfoIsInStandardLibrary - Given a builtin type, returns whether the type
/// info for that type is defined in the standard library.
static bool TypeInfoIsInStandardLibrary(const BuiltinType *Ty) {
// Itanium C++ ABI 2.9.2:
// Basic type information (e.g. for "int", "bool", etc.) will be kept in
// the run-time support library. Specifically, the run-time support
// library should contain type_info objects for the types X, X* and
// X const*, for every X in: void, std::nullptr_t, bool, wchar_t, char,
// unsigned char, signed char, short, unsigned short, int, unsigned int,
// long, unsigned long, long long, unsigned long long, float, double,
// long double, char16_t, char32_t, and the IEEE 754r decimal and
// half-precision floating point types.
switch (Ty->getKind()) {
case BuiltinType::Void:
case BuiltinType::NullPtr:
case BuiltinType::Bool:
case BuiltinType::WChar_S:
case BuiltinType::WChar_U:
case BuiltinType::Char_U:
case BuiltinType::Char_S:
case BuiltinType::UChar:
case BuiltinType::SChar:
case BuiltinType::Short:
case BuiltinType::UShort:
case BuiltinType::Int:
case BuiltinType::UInt:
case BuiltinType::Long:
case BuiltinType::ULong:
case BuiltinType::LongLong:
case BuiltinType::ULongLong:
case BuiltinType::Half:
case BuiltinType::Float:
case BuiltinType::Double:
case BuiltinType::LongDouble:
case BuiltinType::Char16:
case BuiltinType::Char32:
case BuiltinType::Int128:
case BuiltinType::UInt128:
case BuiltinType::OCLImage1d:
case BuiltinType::OCLImage1dArray:
case BuiltinType::OCLImage1dBuffer:
case BuiltinType::OCLImage2d:
case BuiltinType::OCLImage2dArray:
case BuiltinType::OCLImage3d:
case BuiltinType::OCLSampler:
case BuiltinType::OCLEvent:
return true;
case BuiltinType::Dependent:
#define BUILTIN_TYPE(Id, SingletonId)
#define PLACEHOLDER_TYPE(Id, SingletonId) \
case BuiltinType::Id:
#include "clang/AST/BuiltinTypes.def"
llvm_unreachable("asking for RRTI for a placeholder type!");
case BuiltinType::ObjCId:
case BuiltinType::ObjCClass:
case BuiltinType::ObjCSel:
llvm_unreachable("FIXME: Objective-C types are unsupported!");
}
llvm_unreachable("Invalid BuiltinType Kind!");
}
static bool TypeInfoIsInStandardLibrary(const PointerType *PointerTy) {
QualType PointeeTy = PointerTy->getPointeeType();
const BuiltinType *BuiltinTy = dyn_cast<BuiltinType>(PointeeTy);
if (!BuiltinTy)
return false;
// Check the qualifiers.
Qualifiers Quals = PointeeTy.getQualifiers();
Quals.removeConst();
if (!Quals.empty())
return false;
return TypeInfoIsInStandardLibrary(BuiltinTy);
}
/// IsStandardLibraryRTTIDescriptor - Returns whether the type
/// information for the given type exists in the standard library.
static bool IsStandardLibraryRTTIDescriptor(QualType Ty) {
// Type info for builtin types is defined in the standard library.
if (const BuiltinType *BuiltinTy = dyn_cast<BuiltinType>(Ty))
return TypeInfoIsInStandardLibrary(BuiltinTy);
// Type info for some pointer types to builtin types is defined in the
// standard library.
if (const PointerType *PointerTy = dyn_cast<PointerType>(Ty))
return TypeInfoIsInStandardLibrary(PointerTy);
return false;
}
/// ShouldUseExternalRTTIDescriptor - Returns whether the type information for
/// the given type exists somewhere else, and that we should not emit the type
/// information in this translation unit. Assumes that it is not a
/// standard-library type.
static bool ShouldUseExternalRTTIDescriptor(CodeGenModule &CGM,
QualType Ty) {
ASTContext &Context = CGM.getContext();
// If RTTI is disabled, assume it might be disabled in the
// translation unit that defines any potential key function, too.
if (!Context.getLangOpts().RTTI) return false;
if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(RecordTy->getDecl());
if (!RD->hasDefinition())
return false;
if (!RD->isDynamicClass())
return false;
// FIXME: this may need to be reconsidered if the key function
// changes.
if (CGM.getVTables().isVTableExternal(RD))
return true;
if (RD->hasAttr<DLLImportAttr>())
return true;
}
return false;
}
/// IsIncompleteClassType - Returns whether the given record type is incomplete.
static bool IsIncompleteClassType(const RecordType *RecordTy) {
return !RecordTy->getDecl()->isCompleteDefinition();
}
/// ContainsIncompleteClassType - Returns whether the given type contains an
/// incomplete class type. This is true if
///
/// * The given type is an incomplete class type.
/// * The given type is a pointer type whose pointee type contains an
/// incomplete class type.
/// * The given type is a member pointer type whose class is an incomplete
/// class type.
/// * The given type is a member pointer type whoise pointee type contains an
/// incomplete class type.
/// is an indirect or direct pointer to an incomplete class type.
static bool ContainsIncompleteClassType(QualType Ty) {
if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
if (IsIncompleteClassType(RecordTy))
return true;
}
if (const PointerType *PointerTy = dyn_cast<PointerType>(Ty))
return ContainsIncompleteClassType(PointerTy->getPointeeType());
if (const MemberPointerType *MemberPointerTy =
dyn_cast<MemberPointerType>(Ty)) {
// Check if the class type is incomplete.
const RecordType *ClassType = cast<RecordType>(MemberPointerTy->getClass());
if (IsIncompleteClassType(ClassType))
return true;
return ContainsIncompleteClassType(MemberPointerTy->getPointeeType());
}
return false;
}
// CanUseSingleInheritance - Return whether the given record decl has a "single,
// public, non-virtual base at offset zero (i.e. the derived class is dynamic
// iff the base is)", according to Itanium C++ ABI, 2.95p6b.
static bool CanUseSingleInheritance(const CXXRecordDecl *RD) {
// Check the number of bases.
if (RD->getNumBases() != 1)
return false;
// Get the base.
CXXRecordDecl::base_class_const_iterator Base = RD->bases_begin();
// Check that the base is not virtual.
if (Base->isVirtual())
return false;
// Check that the base is public.
if (Base->getAccessSpecifier() != AS_public)
return false;
// Check that the class is dynamic iff the base is.
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl());
if (!BaseDecl->isEmpty() &&
BaseDecl->isDynamicClass() != RD->isDynamicClass())
return false;
return true;
}
void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty) {
// abi::__class_type_info.
static const char * const ClassTypeInfo =
"_ZTVN10__cxxabiv117__class_type_infoE";
// abi::__si_class_type_info.
static const char * const SIClassTypeInfo =
"_ZTVN10__cxxabiv120__si_class_type_infoE";
// abi::__vmi_class_type_info.
static const char * const VMIClassTypeInfo =
"_ZTVN10__cxxabiv121__vmi_class_type_infoE";
const char *VTableName = nullptr;
switch (Ty->getTypeClass()) {
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#define DEPENDENT_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("Non-canonical and dependent types shouldn't get here");
case Type::LValueReference:
case Type::RValueReference:
llvm_unreachable("References shouldn't get here");
case Type::Auto:
llvm_unreachable("Undeduced auto type shouldn't get here");
case Type::Builtin:
// GCC treats vector and complex types as fundamental types.
case Type::Vector:
case Type::ExtVector:
case Type::Complex:
case Type::Atomic:
// FIXME: GCC treats block pointers as fundamental types?!
case Type::BlockPointer:
// abi::__fundamental_type_info.
VTableName = "_ZTVN10__cxxabiv123__fundamental_type_infoE";
break;
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::VariableArray:
// abi::__array_type_info.
VTableName = "_ZTVN10__cxxabiv117__array_type_infoE";
break;
case Type::FunctionNoProto:
case Type::FunctionProto:
// abi::__function_type_info.
VTableName = "_ZTVN10__cxxabiv120__function_type_infoE";
break;
case Type::Enum:
// abi::__enum_type_info.
VTableName = "_ZTVN10__cxxabiv116__enum_type_infoE";
break;
case Type::Record: {
const CXXRecordDecl *RD =
cast<CXXRecordDecl>(cast<RecordType>(Ty)->getDecl());
if (!RD->hasDefinition() || !RD->getNumBases()) {
VTableName = ClassTypeInfo;
} else if (CanUseSingleInheritance(RD)) {
VTableName = SIClassTypeInfo;
} else {
VTableName = VMIClassTypeInfo;
}
break;
}
case Type::ObjCObject:
// Ignore protocol qualifiers.
Ty = cast<ObjCObjectType>(Ty)->getBaseType().getTypePtr();
// Handle id and Class.
if (isa<BuiltinType>(Ty)) {
VTableName = ClassTypeInfo;
break;
}
assert(isa<ObjCInterfaceType>(Ty));
// Fall through.
case Type::ObjCInterface:
if (cast<ObjCInterfaceType>(Ty)->getDecl()->getSuperClass()) {
VTableName = SIClassTypeInfo;
} else {
VTableName = ClassTypeInfo;
}
break;
case Type::ObjCObjectPointer:
case Type::Pointer:
// abi::__pointer_type_info.
VTableName = "_ZTVN10__cxxabiv119__pointer_type_infoE";
break;
case Type::MemberPointer:
// abi::__pointer_to_member_type_info.
VTableName = "_ZTVN10__cxxabiv129__pointer_to_member_type_infoE";
break;
}
llvm::Constant *VTable =
CGM.getModule().getOrInsertGlobal(VTableName, CGM.Int8PtrTy);
llvm::Type *PtrDiffTy =
CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
// The vtable address point is 2.
llvm::Constant *Two = llvm::ConstantInt::get(PtrDiffTy, 2);
VTable = llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Two);
VTable = llvm::ConstantExpr::getBitCast(VTable, CGM.Int8PtrTy);
Fields.push_back(VTable);
}
/// \brief Return the linkage that the type info and type info name constants
/// should have for the given type.
static llvm::GlobalVariable::LinkageTypes getTypeInfoLinkage(CodeGenModule &CGM,
QualType Ty) {
// Itanium C++ ABI 2.9.5p7:
// In addition, it and all of the intermediate abi::__pointer_type_info
// structs in the chain down to the abi::__class_type_info for the
// incomplete class type must be prevented from resolving to the
// corresponding type_info structs for the complete class type, possibly
// by making them local static objects. Finally, a dummy class RTTI is
// generated for the incomplete type that will not resolve to the final
// complete class RTTI (because the latter need not exist), possibly by
// making it a local static object.
if (ContainsIncompleteClassType(Ty))
return llvm::GlobalValue::InternalLinkage;
switch (Ty->getLinkage()) {
case NoLinkage:
case InternalLinkage:
case UniqueExternalLinkage:
return llvm::GlobalValue::InternalLinkage;
case VisibleNoLinkage:
case ExternalLinkage:
if (!CGM.getLangOpts().RTTI) {
// RTTI is not enabled, which means that this type info struct is going
// to be used for exception handling. Give it linkonce_odr linkage.
return llvm::GlobalValue::LinkOnceODRLinkage;
}
if (const RecordType *Record = dyn_cast<RecordType>(Ty)) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(Record->getDecl());
if (RD->hasAttr<WeakAttr>())
return llvm::GlobalValue::WeakODRLinkage;
if (RD->isDynamicClass())
return CGM.getVTableLinkage(RD);
}
return llvm::GlobalValue::LinkOnceODRLinkage;
}
llvm_unreachable("Invalid linkage!");
}
llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(QualType Ty, bool Force) {
// We want to operate on the canonical type.
Ty = CGM.getContext().getCanonicalType(Ty);
// Check if we've already emitted an RTTI descriptor for this type.
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
Out.flush();
StringRef Name = OutName.str();
llvm::GlobalVariable *OldGV = CGM.getModule().getNamedGlobal(Name);
if (OldGV && !OldGV->isDeclaration()) {
assert(!OldGV->hasAvailableExternallyLinkage() &&
"available_externally typeinfos not yet implemented");
return llvm::ConstantExpr::getBitCast(OldGV, CGM.Int8PtrTy);
}
// Check if there is already an external RTTI descriptor for this type.
bool IsStdLib = IsStandardLibraryRTTIDescriptor(Ty);
if (!Force && (IsStdLib || ShouldUseExternalRTTIDescriptor(CGM, Ty)))
return GetAddrOfExternalRTTIDescriptor(Ty);
// Emit the standard library with external linkage.
llvm::GlobalVariable::LinkageTypes Linkage;
if (IsStdLib)
Linkage = llvm::GlobalValue::ExternalLinkage;
else
Linkage = getTypeInfoLinkage(CGM, Ty);
// Add the vtable pointer.
BuildVTablePointer(cast<Type>(Ty));
// And the name.
llvm::GlobalVariable *TypeName = GetAddrOfTypeName(Ty, Linkage);
llvm::Constant *TypeNameField;
// If we're supposed to demote the visibility, be sure to set a flag
// to use a string comparison for type_info comparisons.
ItaniumCXXABI::RTTIUniquenessKind RTTIUniqueness =
CXXABI.classifyRTTIUniqueness(Ty, Linkage);
if (RTTIUniqueness != ItaniumCXXABI::RUK_Unique) {
// The flag is the sign bit, which on ARM64 is defined to be clear
// for global pointers. This is very ARM64-specific.
TypeNameField = llvm::ConstantExpr::getPtrToInt(TypeName, CGM.Int64Ty);
llvm::Constant *flag =
llvm::ConstantInt::get(CGM.Int64Ty, ((uint64_t)1) << 63);
TypeNameField = llvm::ConstantExpr::getAdd(TypeNameField, flag);
TypeNameField =
llvm::ConstantExpr::getIntToPtr(TypeNameField, CGM.Int8PtrTy);
} else {
TypeNameField = llvm::ConstantExpr::getBitCast(TypeName, CGM.Int8PtrTy);
}
Fields.push_back(TypeNameField);
switch (Ty->getTypeClass()) {
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#define DEPENDENT_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("Non-canonical and dependent types shouldn't get here");
// GCC treats vector types as fundamental types.
case Type::Builtin:
case Type::Vector:
case Type::ExtVector:
case Type::Complex:
case Type::BlockPointer:
// Itanium C++ ABI 2.9.5p4:
// abi::__fundamental_type_info adds no data members to std::type_info.
break;
case Type::LValueReference:
case Type::RValueReference:
llvm_unreachable("References shouldn't get here");
case Type::Auto:
llvm_unreachable("Undeduced auto type shouldn't get here");
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::VariableArray:
// Itanium C++ ABI 2.9.5p5:
// abi::__array_type_info adds no data members to std::type_info.
break;
case Type::FunctionNoProto:
case Type::FunctionProto:
// Itanium C++ ABI 2.9.5p5:
// abi::__function_type_info adds no data members to std::type_info.
break;
case Type::Enum:
// Itanium C++ ABI 2.9.5p5:
// abi::__enum_type_info adds no data members to std::type_info.
break;
case Type::Record: {
const CXXRecordDecl *RD =
cast<CXXRecordDecl>(cast<RecordType>(Ty)->getDecl());
if (!RD->hasDefinition() || !RD->getNumBases()) {
// We don't need to emit any fields.
break;
}
if (CanUseSingleInheritance(RD))
BuildSIClassTypeInfo(RD);
else
BuildVMIClassTypeInfo(RD);
break;
}
case Type::ObjCObject:
case Type::ObjCInterface:
BuildObjCObjectTypeInfo(cast<ObjCObjectType>(Ty));
break;
case Type::ObjCObjectPointer:
BuildPointerTypeInfo(cast<ObjCObjectPointerType>(Ty)->getPointeeType());
break;
case Type::Pointer:
BuildPointerTypeInfo(cast<PointerType>(Ty)->getPointeeType());
break;
case Type::MemberPointer:
BuildPointerToMemberTypeInfo(cast<MemberPointerType>(Ty));
break;
case Type::Atomic:
// No fields, at least for the moment.
break;
}
llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
llvm::Module &M = CGM.getModule();
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(M, Init->getType(),
/*Constant=*/true, Linkage, Init, Name);
if (CGM.supportsCOMDAT() && GV->isWeakForLinker())
GV->setComdat(M.getOrInsertComdat(GV->getName()));
// If there's already an old global variable, replace it with the new one.
if (OldGV) {
GV->takeName(OldGV);
llvm::Constant *NewPtr =
llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
OldGV->replaceAllUsesWith(NewPtr);
OldGV->eraseFromParent();
}
// The Itanium ABI specifies that type_info objects must be globally
// unique, with one exception: if the type is an incomplete class
// type or a (possibly indirect) pointer to one. That exception
// affects the general case of comparing type_info objects produced
// by the typeid operator, which is why the comparison operators on
// std::type_info generally use the type_info name pointers instead
// of the object addresses. However, the language's built-in uses
// of RTTI generally require class types to be complete, even when
// manipulating pointers to those class types. This allows the
// implementation of dynamic_cast to rely on address equality tests,
// which is much faster.
// All of this is to say that it's important that both the type_info
// object and the type_info name be uniqued when weakly emitted.
// Give the type_info object and name the formal visibility of the
// type itself.
llvm::GlobalValue::VisibilityTypes llvmVisibility;
if (llvm::GlobalValue::isLocalLinkage(Linkage))
// If the linkage is local, only default visibility makes sense.
llvmVisibility = llvm::GlobalValue::DefaultVisibility;
else if (RTTIUniqueness == ItaniumCXXABI::RUK_NonUniqueHidden)
llvmVisibility = llvm::GlobalValue::HiddenVisibility;
else
llvmVisibility = CodeGenModule::GetLLVMVisibility(Ty->getVisibility());
TypeName->setVisibility(llvmVisibility);
GV->setVisibility(llvmVisibility);
return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
}
/// ComputeQualifierFlags - Compute the pointer type info flags from the
/// given qualifier.
static unsigned ComputeQualifierFlags(Qualifiers Quals) {
unsigned Flags = 0;
if (Quals.hasConst())
Flags |= ItaniumRTTIBuilder::PTI_Const;
if (Quals.hasVolatile())
Flags |= ItaniumRTTIBuilder::PTI_Volatile;
if (Quals.hasRestrict())
Flags |= ItaniumRTTIBuilder::PTI_Restrict;
return Flags;
}
/// BuildObjCObjectTypeInfo - Build the appropriate kind of type_info
/// for the given Objective-C object type.
void ItaniumRTTIBuilder::BuildObjCObjectTypeInfo(const ObjCObjectType *OT) {
// Drop qualifiers.
const Type *T = OT->getBaseType().getTypePtr();
assert(isa<BuiltinType>(T) || isa<ObjCInterfaceType>(T));
// The builtin types are abi::__class_type_infos and don't require
// extra fields.
if (isa<BuiltinType>(T)) return;
ObjCInterfaceDecl *Class = cast<ObjCInterfaceType>(T)->getDecl();
ObjCInterfaceDecl *Super = Class->getSuperClass();
// Root classes are also __class_type_info.
if (!Super) return;
QualType SuperTy = CGM.getContext().getObjCInterfaceType(Super);
// Everything else is single inheritance.
llvm::Constant *BaseTypeInfo =
ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(SuperTy);
Fields.push_back(BaseTypeInfo);
}
/// BuildSIClassTypeInfo - Build an abi::__si_class_type_info, used for single
/// inheritance, according to the Itanium C++ ABI, 2.95p6b.
void ItaniumRTTIBuilder::BuildSIClassTypeInfo(const CXXRecordDecl *RD) {
// Itanium C++ ABI 2.9.5p6b:
// It adds to abi::__class_type_info a single member pointing to the
// type_info structure for the base type,
llvm::Constant *BaseTypeInfo =
ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(RD->bases_begin()->getType());
Fields.push_back(BaseTypeInfo);
}
namespace {
/// SeenBases - Contains virtual and non-virtual bases seen when traversing
/// a class hierarchy.
struct SeenBases {
llvm::SmallPtrSet<const CXXRecordDecl *, 16> NonVirtualBases;
llvm::SmallPtrSet<const CXXRecordDecl *, 16> VirtualBases;
};
}
/// ComputeVMIClassTypeInfoFlags - Compute the value of the flags member in
/// abi::__vmi_class_type_info.
///
static unsigned ComputeVMIClassTypeInfoFlags(const CXXBaseSpecifier *Base,
SeenBases &Bases) {
unsigned Flags = 0;
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl());
if (Base->isVirtual()) {
// Mark the virtual base as seen.
if (!Bases.VirtualBases.insert(BaseDecl).second) {
// If this virtual base has been seen before, then the class is diamond
// shaped.
Flags |= ItaniumRTTIBuilder::VMI_DiamondShaped;
} else {
if (Bases.NonVirtualBases.count(BaseDecl))
Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;
}
} else {
// Mark the non-virtual base as seen.
if (!Bases.NonVirtualBases.insert(BaseDecl).second) {
// If this non-virtual base has been seen before, then the class has non-
// diamond shaped repeated inheritance.
Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;
} else {
if (Bases.VirtualBases.count(BaseDecl))
Flags |= ItaniumRTTIBuilder::VMI_NonDiamondRepeat;
}
}
// Walk all bases.
for (const auto &I : BaseDecl->bases())
Flags |= ComputeVMIClassTypeInfoFlags(&I, Bases);
return Flags;
}
static unsigned ComputeVMIClassTypeInfoFlags(const CXXRecordDecl *RD) {
unsigned Flags = 0;
SeenBases Bases;
// Walk all bases.
for (const auto &I : RD->bases())
Flags |= ComputeVMIClassTypeInfoFlags(&I, Bases);
return Flags;
}
/// BuildVMIClassTypeInfo - Build an abi::__vmi_class_type_info, used for
/// classes with bases that do not satisfy the abi::__si_class_type_info
/// constraints, according ti the Itanium C++ ABI, 2.9.5p5c.
void ItaniumRTTIBuilder::BuildVMIClassTypeInfo(const CXXRecordDecl *RD) {
llvm::Type *UnsignedIntLTy =
CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);
// Itanium C++ ABI 2.9.5p6c:
// __flags is a word with flags describing details about the class
// structure, which may be referenced by using the __flags_masks
// enumeration. These flags refer to both direct and indirect bases.
unsigned Flags = ComputeVMIClassTypeInfoFlags(RD);
Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));
// Itanium C++ ABI 2.9.5p6c:
// __base_count is a word with the number of direct proper base class
// descriptions that follow.
Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, RD->getNumBases()));
if (!RD->getNumBases())
return;
llvm::Type *LongLTy =
CGM.getTypes().ConvertType(CGM.getContext().LongTy);
// Now add the base class descriptions.
// Itanium C++ ABI 2.9.5p6c:
// __base_info[] is an array of base class descriptions -- one for every
// direct proper base. Each description is of the type:
//
// struct abi::__base_class_type_info {
// public:
// const __class_type_info *__base_type;
// long __offset_flags;
//
// enum __offset_flags_masks {
// __virtual_mask = 0x1,
// __public_mask = 0x2,
// __offset_shift = 8
// };
// };
for (const auto &Base : RD->bases()) {
// The __base_type member points to the RTTI for the base type.
Fields.push_back(ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(Base.getType()));
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
int64_t OffsetFlags = 0;
// All but the lower 8 bits of __offset_flags are a signed offset.
// For a non-virtual base, this is the offset in the object of the base
// subobject. For a virtual base, this is the offset in the virtual table of
// the virtual base offset for the virtual base referenced (negative).
CharUnits Offset;
if (Base.isVirtual())
Offset =
CGM.getItaniumVTableContext().getVirtualBaseOffsetOffset(RD, BaseDecl);
else {
const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
Offset = Layout.getBaseClassOffset(BaseDecl);
};
OffsetFlags = uint64_t(Offset.getQuantity()) << 8;
// The low-order byte of __offset_flags contains flags, as given by the
// masks from the enumeration __offset_flags_masks.
if (Base.isVirtual())
OffsetFlags |= BCTI_Virtual;
if (Base.getAccessSpecifier() == AS_public)
OffsetFlags |= BCTI_Public;
Fields.push_back(llvm::ConstantInt::get(LongLTy, OffsetFlags));
}
}
/// BuildPointerTypeInfo - Build an abi::__pointer_type_info struct,
/// used for pointer types.
void ItaniumRTTIBuilder::BuildPointerTypeInfo(QualType PointeeTy) {
Qualifiers Quals;
QualType UnqualifiedPointeeTy =
CGM.getContext().getUnqualifiedArrayType(PointeeTy, Quals);
// Itanium C++ ABI 2.9.5p7:
// __flags is a flag word describing the cv-qualification and other
// attributes of the type pointed to
unsigned Flags = ComputeQualifierFlags(Quals);
// Itanium C++ ABI 2.9.5p7:
// When the abi::__pbase_type_info is for a direct or indirect pointer to an
// incomplete class type, the incomplete target type flag is set.
if (ContainsIncompleteClassType(UnqualifiedPointeeTy))
Flags |= PTI_Incomplete;
llvm::Type *UnsignedIntLTy =
CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);
Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));
// Itanium C++ ABI 2.9.5p7:
// __pointee is a pointer to the std::type_info derivation for the
// unqualified type being pointed to.
llvm::Constant *PointeeTypeInfo =
ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(UnqualifiedPointeeTy);
Fields.push_back(PointeeTypeInfo);
}
/// BuildPointerToMemberTypeInfo - Build an abi::__pointer_to_member_type_info
/// struct, used for member pointer types.
void
ItaniumRTTIBuilder::BuildPointerToMemberTypeInfo(const MemberPointerType *Ty) {
QualType PointeeTy = Ty->getPointeeType();
Qualifiers Quals;
QualType UnqualifiedPointeeTy =
CGM.getContext().getUnqualifiedArrayType(PointeeTy, Quals);
// Itanium C++ ABI 2.9.5p7:
// __flags is a flag word describing the cv-qualification and other
// attributes of the type pointed to.
unsigned Flags = ComputeQualifierFlags(Quals);
const RecordType *ClassType = cast<RecordType>(Ty->getClass());
// Itanium C++ ABI 2.9.5p7:
// When the abi::__pbase_type_info is for a direct or indirect pointer to an
// incomplete class type, the incomplete target type flag is set.
if (ContainsIncompleteClassType(UnqualifiedPointeeTy))
Flags |= PTI_Incomplete;
if (IsIncompleteClassType(ClassType))
Flags |= PTI_ContainingClassIncomplete;
llvm::Type *UnsignedIntLTy =
CGM.getTypes().ConvertType(CGM.getContext().UnsignedIntTy);
Fields.push_back(llvm::ConstantInt::get(UnsignedIntLTy, Flags));
// Itanium C++ ABI 2.9.5p7:
// __pointee is a pointer to the std::type_info derivation for the
// unqualified type being pointed to.
llvm::Constant *PointeeTypeInfo =
ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(UnqualifiedPointeeTy);
Fields.push_back(PointeeTypeInfo);
// Itanium C++ ABI 2.9.5p9:
// __context is a pointer to an abi::__class_type_info corresponding to the
// class type containing the member pointed to
// (e.g., the "A" in "int A::*").
Fields.push_back(
ItaniumRTTIBuilder(CXXABI).BuildTypeInfo(QualType(ClassType, 0)));
}
llvm::Constant *ItaniumCXXABI::getAddrOfRTTIDescriptor(QualType Ty) {
return ItaniumRTTIBuilder(*this).BuildTypeInfo(Ty);
}
void ItaniumCXXABI::EmitFundamentalRTTIDescriptor(QualType Type) {
QualType PointerType = getContext().getPointerType(Type);
QualType PointerTypeConst = getContext().getPointerType(Type.withConst());
ItaniumRTTIBuilder(*this).BuildTypeInfo(Type, true);
ItaniumRTTIBuilder(*this).BuildTypeInfo(PointerType, true);
ItaniumRTTIBuilder(*this).BuildTypeInfo(PointerTypeConst, true);
}
void ItaniumCXXABI::EmitFundamentalRTTIDescriptors() {
QualType FundamentalTypes[] = {
getContext().VoidTy, getContext().NullPtrTy,
getContext().BoolTy, getContext().WCharTy,
getContext().CharTy, getContext().UnsignedCharTy,
getContext().SignedCharTy, getContext().ShortTy,
getContext().UnsignedShortTy, getContext().IntTy,
getContext().UnsignedIntTy, getContext().LongTy,
getContext().UnsignedLongTy, getContext().LongLongTy,
getContext().UnsignedLongLongTy, getContext().HalfTy,
getContext().FloatTy, getContext().DoubleTy,
getContext().LongDoubleTy, getContext().Char16Ty,
getContext().Char32Ty,
};
for (const QualType &FundamentalType : FundamentalTypes)
EmitFundamentalRTTIDescriptor(FundamentalType);
}
/// What sort of uniqueness rules should we use for the RTTI for the
/// given type?
ItaniumCXXABI::RTTIUniquenessKind ItaniumCXXABI::classifyRTTIUniqueness(
QualType CanTy, llvm::GlobalValue::LinkageTypes Linkage) const {
if (shouldRTTIBeUnique())
return RUK_Unique;
// It's only necessary for linkonce_odr or weak_odr linkage.
if (Linkage != llvm::GlobalValue::LinkOnceODRLinkage &&
Linkage != llvm::GlobalValue::WeakODRLinkage)
return RUK_Unique;
// It's only necessary with default visibility.
if (CanTy->getVisibility() != DefaultVisibility)
return RUK_Unique;
// If we're not required to publish this symbol, hide it.
if (Linkage == llvm::GlobalValue::LinkOnceODRLinkage)
return RUK_NonUniqueHidden;
// If we're required to publish this symbol, as we might be under an
// explicit instantiation, leave it with default visibility but
// enable string-comparisons.
assert(Linkage == llvm::GlobalValue::WeakODRLinkage);
return RUK_NonUniqueVisible;
}
// Find out how to codegen the complete destructor and constructor
namespace {
enum class StructorCodegen { Emit, RAUW, Alias, COMDAT };
}
static StructorCodegen getCodegenToUse(CodeGenModule &CGM,
const CXXMethodDecl *MD) {
if (!CGM.getCodeGenOpts().CXXCtorDtorAliases)
return StructorCodegen::Emit;
// The complete and base structors are not equivalent if there are any virtual
// bases, so emit separate functions.
if (MD->getParent()->getNumVBases())
return StructorCodegen::Emit;
GlobalDecl AliasDecl;
if (const auto *DD = dyn_cast<CXXDestructorDecl>(MD)) {
AliasDecl = GlobalDecl(DD, Dtor_Complete);
} else {
const auto *CD = cast<CXXConstructorDecl>(MD);
AliasDecl = GlobalDecl(CD, Ctor_Complete);
}
llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(AliasDecl);
if (llvm::GlobalValue::isDiscardableIfUnused(Linkage))
return StructorCodegen::RAUW;
// FIXME: Should we allow available_externally aliases?
if (!llvm::GlobalAlias::isValidLinkage(Linkage))
return StructorCodegen::RAUW;
if (llvm::GlobalValue::isWeakForLinker(Linkage)) {
// Only ELF supports COMDATs with arbitrary names (C5/D5).
if (CGM.getTarget().getTriple().isOSBinFormatELF())
return StructorCodegen::COMDAT;
return StructorCodegen::Emit;
}
return StructorCodegen::Alias;
}
static void emitConstructorDestructorAlias(CodeGenModule &CGM,
GlobalDecl AliasDecl,
GlobalDecl TargetDecl) {
llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(AliasDecl);
StringRef MangledName = CGM.getMangledName(AliasDecl);
llvm::GlobalValue *Entry = CGM.GetGlobalValue(MangledName);
if (Entry && !Entry->isDeclaration())
return;
auto *Aliasee = cast<llvm::GlobalValue>(CGM.GetAddrOfGlobal(TargetDecl));
llvm::PointerType *AliasType = Aliasee->getType();
// Create the alias with no name.
auto *Alias = llvm::GlobalAlias::create(
AliasType->getElementType(), 0, Linkage, "", Aliasee, &CGM.getModule());
// Switch any previous uses to the alias.
if (Entry) {
assert(Entry->getType() == AliasType &&
"declaration exists with different type");
Alias->takeName(Entry);
Entry->replaceAllUsesWith(Alias);
Entry->eraseFromParent();
} else {
Alias->setName(MangledName);
}
// Finally, set up the alias with its proper name and attributes.
CGM.setAliasAttributes(cast<NamedDecl>(AliasDecl.getDecl()), Alias);
}
void ItaniumCXXABI::emitCXXStructor(const CXXMethodDecl *MD,
StructorType Type) {
auto *CD = dyn_cast<CXXConstructorDecl>(MD);
const CXXDestructorDecl *DD = CD ? nullptr : cast<CXXDestructorDecl>(MD);
StructorCodegen CGType = getCodegenToUse(CGM, MD);
if (Type == StructorType::Complete) {
GlobalDecl CompleteDecl;
GlobalDecl BaseDecl;
if (CD) {
CompleteDecl = GlobalDecl(CD, Ctor_Complete);
BaseDecl = GlobalDecl(CD, Ctor_Base);
} else {
CompleteDecl = GlobalDecl(DD, Dtor_Complete);
BaseDecl = GlobalDecl(DD, Dtor_Base);
}
if (CGType == StructorCodegen::Alias || CGType == StructorCodegen::COMDAT) {
emitConstructorDestructorAlias(CGM, CompleteDecl, BaseDecl);
return;
}
if (CGType == StructorCodegen::RAUW) {
StringRef MangledName = CGM.getMangledName(CompleteDecl);
auto *Aliasee = cast<llvm::GlobalValue>(CGM.GetAddrOfGlobal(BaseDecl));
CGM.addReplacement(MangledName, Aliasee);
return;
}
}
// The base destructor is equivalent to the base destructor of its
// base class if there is exactly one non-virtual base class with a
// non-trivial destructor, there are no fields with a non-trivial
// destructor, and the body of the destructor is trivial.
if (DD && Type == StructorType::Base && CGType != StructorCodegen::COMDAT &&
!CGM.TryEmitBaseDestructorAsAlias(DD))
return;
llvm::Function *Fn = CGM.codegenCXXStructor(MD, Type);
if (CGType == StructorCodegen::COMDAT) {
SmallString<256> Buffer;
llvm::raw_svector_ostream Out(Buffer);
if (DD)
getMangleContext().mangleCXXDtorComdat(DD, Out);
else
getMangleContext().mangleCXXCtorComdat(CD, Out);
llvm::Comdat *C = CGM.getModule().getOrInsertComdat(Out.str());
Fn->setComdat(C);
} else {
CGM.maybeSetTrivialComdat(*MD, *Fn);
}
}
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